N13549.xml

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            <title>Conjectures upon the nature and motion of meteors, which are above the atmosphere. By Thomas Clap, A.M. late president of Yale-College.</title>
            <author>Clap, Thomas, 1703-1767.</author>
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            <idno type="STC">Evans 17113</idno>
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            <idno type="EVANS-CITATION">99020074</idno>
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            <title>Early American Imprints, 1639-1800 ; no. 17113.</title>
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                  <title>Conjectures upon the nature and motion of meteors, which are above the atmosphere. By Thomas Clap, A.M. late president of Yale-College.</title>
                  <author>Clap, Thomas, 1703-1767.</author>
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                  <publisher>Printed by John Trumbull, for the subscribers.,</publisher>
                  <pubPlace>Norwich [Conn.]: :</pubPlace>
                  <date>M.DCC.LXXXI. [1781]</date>
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                  <note>Half-title: President Clap, on terrestrial comets.</note>
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               <term>Meteors.</term>
               <term>Comets.</term>
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            <pb facs="tcp:017113_0000_0FA02F49C5F4EAE8"/>
            <pb facs="tcp:017113_0001_0FA02F4A826C77D8"/>
            <p>PRESIDENT CLAP, ON TERRESTRIAL COMETS.</p>
         </div>
         <div type="title_page">
            <pb facs="tcp:017113_0002_0FA02F4B495079C8"/>
            <p>CONJECTURES UPON THE NATURE AND MOTION OF METEORS, WHICH ARE ABOVE THE ATMOSPHERE.</p>
            <p>BY THOMAS CLAP, A. M. LATE PRESIDENT OF YALE COLLEGE.</p>
            <p>
               <hi>NORWICH:</hi> PRINTED BY JOHN TRUMBULL, FOR THE SUBSCRIBERS. <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
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            <pb facs="tcp:017113_0003_0FA02F4BF24EFF70"/>
            <head>CONJECTURES UPON THE NATURE AND MOTION OF METEORS, &amp;c.</head>
            <p>UPON ſeveral obſervations made upon ſundry Meteors, which have appeared in Europe and New-England, I have collected the following general phaenomena:</p>
            <p n="1">I. THEY appear like round balls of fire, or globes of red hot iron, or white hot iron, ready to melt, as large as the ſun or moon, in the meridian, com­monly ſurrounded with a flame which appears like a tail, with ſtreams and ſparkles net ſo bright as the body. They frequently exceed the light of the moon, and in ſome inſtances that of the ſun, ſo as to make a ſhadow in the cleareſt ſunſhine.</p>
            <p n="2">II. THESE Meteors have been ſeen paſſing through the air, at all points of the compaſs, over a ſpace of ground above 100, and ſometimes above 500 miles long, and above 100 miles wide, with an exceeding great veloſity. I could never get ob­ſervations accurate enough, to determine the velocity with any degree of exactneſs. Doctor Halley ſuppoſes it to be above 300 miles, and Doctor Pringle about 1000, in a minute. I rather ſuppoſe it does not exceed 500, for the reaſons hereafter mentioned.</p>
            <p n="3">III. To each particular perſon obſerving, who ſtands in or near the line of their courſe, they ſeem to riſe while they are coming towards him, and to fall when they are going from him, as the ſun riſes and ſets, ſeemingly at a ſmall diſtance. But by comparing the obſervations made by ſeveral perſons ſtanding a little out of the line of their courſe, at the diſtance of 50, 100, or 500 miles from each other, it ap­pears that at their firſt approach or appearance they are 50 or 100 miles diſtant from the earth; then they come within 20 or 30 miles of it; and afterwards are at the diſtance of 50 or 100 miles again; which different diſtances ſeem to ariſe principally from the curvatur of the earth. Or if theſe ſeveral diſtances of any one Meteor have not been accurately determined on both ſides of its neareſt approach, yet it is evident, that ſo<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>e Meteors, during the time in which they have been obſerved, have been coming nearer to the earth, and others going farther from it.</p>
            <p n="4">
               <pb n="6" facs="tcp:017113_0004_0FA02F4D31625D50"/>
IV. <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> tranſit, m<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ke a continual whizzing or humming <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> like a great number of drums, or g<gap reason="illegible" resp="#PDCC" extent="2 letters">
                  <desc>••</desc>
               </gap>s, or diſtant <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> heard preſently after they paſs by. And about <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>he <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> neareſt the earth, or a little after, the body of the Meteor ſeems to <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> 
               <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>omb, with a great exploſion of flames, ſtreams, and ſparkles; and <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> after the<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>e is a very loud noiſe, ſometimes like terrible thunder, ſo as to <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
               </gap> the ground and houſes, like an earthquake, or like the report of a very large <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> 
               <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>and; or, as ſome ſay, as loud as a thouſand cannon fired together, at 20 or 30 miles diſtance. And when it is cloudy, noiſes <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ke diſtant cannon or rumbling thunder, have been heard paſſing through the air, without any diſtinct light.</p>
            <p n="5">V. ALTHOUGH theſe Meteors, by reaſon of their extreme velocity and great diſ­tance, generally become inviſible in about a minute after they paſs by; and as they recede from any perſon, preſently make but a ſmall angle with the ho<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>zon, and ſeem to be ſuddenly intercepted by horizontal clouds, houſes, &amp;c. yet there is no ſufficient evidence that any of theſe high Meteors, which have moved 100 miles or more, ever did really fall to the ground, or become wholly extinct; though after the emiſſion of ſo much of their fire in the exploſion, they are not ſo bright, and have no flame or tails.</p>
            <p n="6">VI. THESE Meteors generally appear as often or oftener than once in 20 or 30 years. Near ten of them have been ſeen in England within theſe 100 years; as re­lated in the P<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> of. Tranſ. Abr. vol. II. page 200; vol. IV. by Jones, part II. page 134 135, 136, 137, 150; vol. VIII. page 121, 123; with that in 1758, ingeni­ouſly treated upon by Doctor Pringle. Three or f<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ur ſuch Meteors have been ob­ſerved in New England within theſe 50 years; but as they have been generally ſup­poſed to be of the ſame nature with thunder, lightning, ſhooting ſtars, and ſuch like lower Me<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>eors, which ſeem to have no exiſtence above two or three minutes, there have not been ſuch critical obſervations made upon them as I could wiſh may be made hereafter. Yet theſe general phaenomena, I take to be as certain as can ordi­na<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>y be collected from ſuch ſudden, tranſient, and unexpected obſervations, gene­rally made by the lower ſort of people: And have therefore been led to conjecture a new Theory of the nature and motion of theſe high Meteors.</p>
            <p>Now to aſſign a natural cauſe or reaſon for any thing, is to reſolve it into the ge­neral laws of nature, by which the wiſe Creator governs the world; and to ſhew its connection with other things, according to thoſe general laws by which we find the univerſe is governed, ſo far as we are acquainted with it. And the fewer laws we have recourſe to, which will ſolve all the apparent phaenomena, the greater is the probability that we have hit upon the true theory. And,</p>
            <p n="1">I. IF the apparent diameter of theſe fiery globes is equal to thoſe of the ſun or moon, in the meridian, and ſubtends an angle of above half a degree, at the diſtance of 50 miles from the obſerver, then it is evident that their real diameter is half a mile at leaſt.</p>
            <p n="2">II. IT ſeems evident that theſe globes are ſolid and firm, at leaſt as to the ex­ternal parts.</p>
            <p n="1">1. BECAUSE, they preſerve their globular ſhape and motion throughout their whole courſe, and after the exploſion. For if they conſiſted only of inflammable
<pb n="7" facs="tcp:017113_0005_0FA02F4DA10DC2F0"/>matter, of the nature of pulvis fulminans, or a train of gun-powder, fired at one and, (as ſome of the lower Meteors ſeem to do) there would be no probability that they would inva<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>iably preſerve their exact globular ſhape; but would melt down, bu<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>n up, or diſſipate with ſuch an intenſe heat, as muſt cauſe or accompany ſuch a vaſt exploſ<gap reason="illegible" resp="#PDCC" extent="3 letters">
                  <desc>•••</desc>
               </gap> of flame and ſound.</p>
            <p n="2">2. BECAUSE, they are ſtrong and firm enough to withſtand the force of ſo great a ſhock as is given at the exploſion. The noiſe is generally repreſented as being equal to loud thunder, a large cannon near by, or a thouſand cannon at the diſtance of 20 or 30 miles. And I ſuppoſe that a thouſand cannon fired at the diſtance of 25 miles, give juſt as loud a report as one cannon at the diſtance of a quarter of a mile. The greatneſs of the exploſion being in a ſeſquiplicate ratio of the diſtance heard
<note n="*" place="bottom">
                  <p>The undulations of ſound are propagated from a ſonorific body in concave ſhells, in­creaſing very much like the blowing up of a bladder The whole preſſure of the air upon the inſide of the ſhell, is equal at all magnitudes, taking the whole ſhell together; but leſſer upon each particular part or ſpot, as it grows bigger. The magnitude of the ſound is in proportion to the ſolid content of the ſpherical ſhell; and the audibility of it (at any particu­lar diſtance) is in proportion to the preſſure upon any particular part, at that diſtance. Therefore, as the ſolid content of the ſphere is to the ſuperficies, or as the cube of any number is to the ſquare of the ſame number, ſo is the magnitude of a ſound to the diſtance heard. Or multiply the diſtance by the ſquare root of itſelf, and it gives the magnitude of the ſound.</p>
                  <p>
                     <table>
                        <row>
                           <cell>
                              <hi>Cube.</hi>
                           </cell>
                           <cell>1</cell>
                           <cell>8</cell>
                           <cell>27</cell>
                           <cell>64</cell>
                           <cell>125</cell>
                           <cell>216</cell>
                           <cell>343</cell>
                           <cell>512</cell>
                           <cell>729</cell>
                           <cell>1000</cell>
                           <cell>
                              <hi>Magnitude.</hi>
                           </cell>
                        </row>
                        <row>
                           <cell>
                              <hi>Square.</hi>
                           </cell>
                           <cell>1</cell>
                           <cell>4</cell>
                           <cell>9</cell>
                           <cell>16</cell>
                           <cell>25</cell>
                           <cell>36</cell>
                           <cell>49</cell>
                           <cell>64</cell>
                           <cell>81</cell>
                           <cell>100</cell>
                           <cell>
                              <hi>Diſtance.</hi>
                           </cell>
                        </row>
                        <row>
                           <cell>
                              <hi>Root.</hi>
                           </cell>
                           <cell>1</cell>
                           <cell>2</cell>
                           <cell>3</cell>
                           <cell>4</cell>
                           <cell>5</cell>
                           <cell>6</cell>
                           <cell>7</cell>
                           <cell>8</cell>
                           <cell>9</cell>
                           <cell>10</cell>
                           <cell> </cell>
                        </row>
                     </table>
                  </p>
                  <p>
                     <hi>Thus in the exploſion of gun-powder: ſuppoſing</hi> 31 <hi>cubic inches to a pound.</hi>
                  </p>
                  <p>
                     <table>
                        <row>
                           <cell>
                              <hi>Quantity.</hi> I <hi>Cubic inches,</hi>
                           </cell>
                           <cell>1</cell>
                           <cell>310 : 10<hi>lb</hi>
                           </cell>
                           <cell>620 : 20<hi>lb.</hi>
                           </cell>
                           <cell>930 : 30<hi>lb.</hi>
                           </cell>
                           <cell>1240: 40<hi>lb.</hi>
                           </cell>
                        </row>
                        <row>
                           <cell>
                              <hi>Diſtance.</hi> I <hi>Miles,</hi> -</cell>
                           <cell>1 1-2</cell>
                           <cell>68</cell>
                           <cell>109</cell>
                           <cell>141</cell>
                           <cell>173</cell>
                        </row>
                     </table>
                  </p>
                  <p>
                     <hi>So the found of a bell according to its weight.</hi>
                  </p>
                  <p>
                     <table>
                        <row>
                           <cell>
                              <hi>Quantity.</hi>
                           </cell>
                           <cell>1 <hi>oz.</hi>
                           </cell>
                           <cell>16 : 1<hi>lb</hi>
                           </cell>
                           <cell>100<hi>lb.</hi>
                           </cell>
                           <cell>500<hi>lb.</hi>
                           </cell>
                           <cell>1000<hi>lb.</hi>
                           </cell>
                        </row>
                        <row>
                           <cell>
                              <hi>Diſtance.</hi>
                           </cell>
                           <cell>5 <hi>rods.</hi>
                           </cell>
                           <cell>30</cell>
                           <cell>640 : 2 <hi>miles.</hi>
                           </cell>
                           <cell>1890 : 6</cell>
                           <cell>3000 : 9</cell>
                        </row>
                     </table>
                  </p>
                  <p>
                     <hi>Mountains, contrary or confuſed winds, and ſuch accidental cauſes, may ſometimes inter­rupt the ſound, ſo as not always to be heard exactly in this proportion.</hi>
                  </p>
               </note>. And if the Meteor is about 30 miles high, where the atmoſphere is 500 times more rare than it is upon the earth, in order to produce the ſame ſound to our ears, it muſt be equal to 500,000 cannon fired upon the earth. And if this exploſion is made by an elaſtick fluid, as violent as gun powder, then the matter of this globe muſt be as ſtrong and firm as the iron of cannon, and the ſides of the ſame proportional thick­neſs, which is about 50 rods, in order to ſtand ſuch a violent ſhock. If this exploſion is cauſed by an elaſtick fluid, <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
               </gap> the nature of electrical fire, as I ſhall afterwards ſhew, then the firmneſs of the globe muſt be almoſt the ſame. For when a body is charged with it, at or near the inſtant when it is diſcharged, the ſire is retained in it with as great a force, as that with which it is diſcharged, or would ſtrike againſt another body. So that the force with which the fire goes out, by any elaſtick ſpring, or repulfive power, is impreſſed on the body it leaves. Or if it be drawn out by the attraction of ſome other body, the force of that attraction is taken off from the body it leaves, which will have the ſame effects upon it. And hence a large phial or jarr, when it is overcharged with electrical fire, will ſometimes burſt, like a bomb, and that although it was ſtrong enough to withſtand the weight or expanſion of the air, which is 15lb. on every ſuperficial inch; and ſuch a preſſure upon a ſphere half a mile in diameter, will lie above 5,000,000lb</p>
            <p>IF it ſhould be objected, the clouds are not ſolid bodies, and yet they emit a vio­lent exploſion;—to this I reply, that the exploſion of thunder and lightning is but very ſmall, in compariſon with that of a Meteor; for, thunder is rarely heard 10 miles, whereas, a Meteor may be heard above 100; and the thunder muſt be within half a mi<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>e, to be heard as loud as a Meteor at the diſtance of 30. And upon computation of the different diſtances and rarity of the air, it will appear, that the
<pb n="8" facs="tcp:017113_0006_0FA02F4E4B1E86F0"/>exploſion of thunder is not a 10,000th part ſo great as that of a ſuperior Meteor; and yet a cloud, containing 5,000,000 t<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ns of water, when it diſcharges it<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> electrical fire, re<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>oils as much as a cannon, in proportion to its weight, and is ſo violently agitated, that the ſmall bubbles are ſuddenly daſhed together into drops, which im­mediately fall down in rain. And if the exploſion of a Meteor is ſo great, when the noiſe heard is only equal to the report of a ſingle cannon near by; how great muſt it be in thoſe inſtances, where it cauſes an earthquake 40 or 50 miles round? It ſeems impoſſible that there ſhould be ſuch a prodigious forcible exploſion, without making an alteration in its perfect globular ſhape, unleſs it be very rigid and firm
<note n="*" place="bottom">
                  <hi>Since theſe balls of fire have been obſerved to accompany earthquakes, I would propoſe it, to be conſidered, whether the exploſion of Meteors may not oftentimes be the cauſe of earthquakes, as well as the eruption of ſubterraneous fires.</hi>
               </note>.</p>
            <p n="3">3. THEIR ſolidity appears from their extreme velocity for many hundreds of miles: For, if a meer flame, ſmoke, or powder, or any thing not ſtrongly cement­ed together, was ſhot out of a cannon at the velocity of 500 miles a minute, it would immediately diffipate or diſſolve: Or, if ſo great a body ſhould continue to­gether, it would neceſſarily drive before it a large column of air, which, by the re­ſiſt<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>nce of the <hi>vis inertiae,</hi> would be extremely condenſed, and the friction of it, by the ſides of the Meteor, would preſently wear it away, unleſs it was very hard and fi<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>m. The round ball always runs away, and leaves the flame, tail and ſparkles be­hind it; juſt as a cannon ball leaves the fire and ſmoke, or the nucleus of a comet runs before its tail. Upon theſe conſiderations, it ſeems evident, that the globe of theſe Meteors is a firm, ſolid ſubſtance; at leaſt, as to the external part.—I would, then, obſerve,</p>
            <p n="3">III. THERE is a continued whizzing, humming, or rumbling noiſe, like diſtant drums, guns, or thunder, made by theſe Meteors, and heard preſently after they paſs b<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>, about a quarter ſo loud as the exploſion: I ſuppoſe this is cauſed by the friction of the Meteor upon the atmoſphere;—for a cannon ball, of ſix inches in diameter, paſſing through the air, with 1-25th part of the velocity of the Meteor, will make a humming noiſe, which is generally heard two miles. Now, if we multiply the ſquare of the difference of the velocities, into the ſquare of the difference of the dia­meters, we ſhall find that the reſiſtance of the air upon the Meteor is, to that upon a cannon ball, as 17,000,000,000 to 1.
<note n="†" place="bottom">
                  <hi>See Newton's Princip. Math. Book</hi> II. <hi>Prop.</hi> 35. <hi>Cor.</hi> 
                  <gap reason="illegible" resp="#PDCC" extent="1 letter">
                     <desc>•</desc>
                  </gap>.</note> And 6,700,000 being the ſquare of that number of which 17,000,000,000 is the cube, will repreſent the proportion of the diſtance in which the humming of the Meteor will be heard farther than that of a cannon-ball: And being diminiſhed to a 500th part on account of the rarity of the atmoſphere, the proportion will be as 13,400 to 1. And becauſe the humming of
<pb n="9" facs="tcp:017113_0007_0FA02F4F01A4DE30"/>the cannon-ball is heard but a 50th part ſo far as the report of a cannon, that num­ber muſt be divided by 50, which will make the humming noiſe of the Meteor equal to the report of 268 cannon, at the diſtance of 25 miles. And the exproſion of the Meteor being repreſented to be equal to 100 cannon at that diſtance, the humming­n<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ſe will be 14th part of it. And this humming noiſe will be leſs, as the diſtance or altitude of the Meteor is greater.</p>
            <p n="4">IV. THE great exploſion and flame attending theſe Meteors, is cauſed by the diſcharge of electrical fire, collected by the friction of the atmoſphere, and emitted about the time, or a little after, it approaches neareſt to the earth, and becomes overcharged. I ſuppoſe electrical fire is not eſſentially different from common fire, and is a kind of univerſal element diffuſed, in ſome degree, into almoſt all bodies in the univerſe, and, by friction, may be collected into a much greater quantity in ſome particular bodies: And, when the whole ſuddenly ruſhes out in one place or ſtream, it is there ſo greatly collected or condenſed, like the rays of the ſun in a focus, that it becomes common fire, capable of inflaming any combuſtible matter; and, by the extreme celerity of its motion, ſo violently agitates the air, as that its elaſtick ſpring becomes ſenſible to the ear. Common experience teaches, that when a col­lection of viſible fire is once begun, the friction of the air upon it, at the velocity of half a mile a minute (as in the blowing of a pair of bellows) will inflame and increaſe it to a very great degree: And, therefore, it is reaſonable to ſuppoſe, that the fric­tion of the air, at the velocity of 1000 half miles in a minute, (the force of which is 1,000,000 to 1) will collect fire where it was not begun before, or but in a low degree; as all bodies grow warm by friction: And, we find by experience, that fire is often collected by ſoft bodies, which do not make ſo great a reſiſtance as conden­ſed air, though moved with a velocity much <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>eſs than that of a Meteor.—Dr. Boer­have, on Chymiſtry, page 249, ſpeaking of collecting fire by friction, ſays, <q>The ſurfaces of two bodies being applied together, one may paſs ſo ſwiftly by the other, as that nothing but fire, the ſwifteſt body in nature, can ſucceed immediately into the vacant places; and by that means it becomes collected, in the path of the moving body, and ſo it has, as it were, a fiery atmoſphere around it. And, (page 231) that balls exploded in the night, out of great guns, grow h<gap reason="illegible" resp="#PDCC" extent="1 letter">
                     <desc>•</desc>
                  </gap>t in their paſſage through the air, ſo as ſometimes to appear ignited.</q> And if a cannon-ball will collect ſome viſible degree of electrical fire, then the Met<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>or, which <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
               </gap> above twenty five times the velocity, and conſequently above ſix hundred times the ſtruction, may collect ſuch a quantity of electrical fire, as may be ſufficient to anſwer all the phaenomena. For a ſoft piece of leather moving upon an electrical globe or tu<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>e, with the velocity of two and an half feet per ſecond, or 150 feet, which is a thirty fifth part of a mile, in a minute, will collect a large quantity of electrical fire in a very ſhort time. And I ſuppoſe 150 ſuperficial inches of leather, paſſing over an electrical globe or tube, with the velocity of 150 feet a minute, and each inch p<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ſſed with a force equal to the weight of one pound, will be ſufficient to raiſe a large ſpa<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>k or ſhap of electrical fire; eſpecially after the globe is once ſufficiently warmed. The mo<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ion of the leather being at the rate of a thirty-fifth part of a mile a minute, and that of the Meteor 500 miles, the proportion of their velocities is as 1 to 17,500; and the momentum or effect produced will be juſt the ſame, whether we take the number of pounds weight in the air (preſſing upon the globe) at the velocity of the Mete<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>, or elſe 17,500 times ſo many pounds at the velocity of the leather.</p>
            <p>A GLORE paſſing very ſwiftly through the air, drives before it a column of air al­moſt equal to itſelf. The elaſtick force of the air will not be ſufficient to overcome
<pb n="10" facs="tcp:017113_0008_0FA02F4FADE67530"/>its vis inertiae, ſo as ſuddenly to protrude the air much before it, or on either fide. By the mo<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> of ſound, we ſee that the elaſti<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>k ſpring o<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> the air will not move it more than 12 miles in a minute, which being no a fortieth part of the velocity of a Meteor, is very inconſiderable in this caſe. And as action and re<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ction are always equal, the vis <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
               </gap> of the air, and <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
               </gap> velocity communicated to it, by its reſiſt <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>nce againſt the Meteor, makes the ſ<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>me action upon the Meteor as it would do <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>f the air w<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> non elaſtick
<note n="*" place="bottom">News. Prin. B. II. Prop. 33. Cor. 3.</note>. The Meteor in two minutes moves through a cilinder of air 1000 males long and hal<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> a mile in diameter; which being taken one place with ano­ther, 500 times rarer than common air, is equal in weight to two miles of common air or 12 feet of water; which, upon computation of 76lb. for every cubic foot, is 5,000,000,000lb. As the Mete<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> moves 17,500 times faſter than the <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ea<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ber on the tube, multiply the number of pounds by that <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>um, and the product will be 87,500,000,000,000, equal to the number of pounds, moving with the velocity of the <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ea­ther, which being divided by 150lb. (which make one electrical ſnap) the quotient will be 583,000,000,000, the number of electrica, ſnaps collected.</p>
            <p>AND that the Meteor will contain ſuch a quantity, is evident, becauſe a phial holding a p<gap reason="illegible" resp="#PDCC" extent="2 letters">
                  <desc>••</desc>
               </gap>t charged with electrical fire, will give a ſnap which can be heard 50 feet, or 100th part of a mile. A cannon is heard 100 miles, which is 10,000 times ſo far as the phial; which being multiplied by the ſquare root of itſelf, gives the quantity of the expreſive force, or ſound, which is heard ſo far. Then 10,000×100=1,000,000, the number of electrical ſnaps which are equal to the report of a cannon, and conſequently 500,000,000,000 ſnaps are equal to 500,000 cannon. N<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>w the Meteor being a ſphere ha<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>f a mile in diameter, contains 574,000,000,000 pints, which wi<gap reason="illegible" resp="#PDCC" extent="2 letters">
                  <desc>••</desc>
               </gap> give the number of ſnaps before-mentioned equal to 500,000 cannon; beſides a ſeventh part overplus which may remain in the Meteor.</p>
            <p>AND to ſhew that 1,000,000 electrical ſnaps are equal to the report of a cannon: I ſuppoſe that a quantity of powder equal to a cube of near <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
               </gap> 10th part of an inch, on ea<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>h ſide, being fi<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ed out of a proper inſtrument, will make a report which may be heard 50 feet, like an electrical ſnap; and 1,000,000 ſuch quantit<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>es, which is about 20lb. being fired out of a cannon, will be heard 100 miles.</p>
            <p>As all theſe proportions agree among themſelves, it is probable they may be near the truth; but if they are not, they will equally ſerve to end the mind into a concep­tion, how it is poſſible that ſuch a vaſt ſolid body may be ſo charged with electrical fire, as to give an exploſion equal to the report of a cannon near by, or to 1000 can­non at the diſtance of 30 miles.</p>
            <p n="5">V. THIS mighty body, which if it be near as ſolid as iron, muſt weigh about 2,000,000,000 tons, cannot be raiſed up, near 100 miles from the earth, by any laws of nature that we are acquainted with. Water, when rarified into the fineſt m<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ſts or bubbles, cannot be carried up above 3 or 4 miles by the weight of the at­moſphere; and when it is condenſed to abou<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> an 800th part of the weight in its na­tural ſtate, it immediately falls down again. Much leſ<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> can it be carried up 40 miles where the air is near 3000 times as light. And it ſeems abſolutely impoſſible, that it ſhould be carried up 100 miles, which is double the utmoſt extent of the atmoſphere. O<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> if we could ſuppoſe it poſſible, that any kind of matter could be rarified ſo as to be carried up ſo high, yet when it comes to be conſolidated, a thouſandth part ſo much as theſe Meteors, it muſt <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ail directly down.</p>
            <p n="6">
               <pb n="11" facs="tcp:017113_0009_0FA02F50ED675E08"/>
VI. IT is beyond the power of any laws of nature, already known, to give ſuch a heavy body ſuch a prodigious projectile velocity, above 20 times ſo great as tha<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> of a cannon ball; and by multip<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ving the difference of their weights into the difference of their ve<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>oc<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ties, it appears that the momentum or force impreſſ<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>d muſt be above 3,000,000,000,000 ſo great. All other bodies moving in the univerſe, that we know of, were at firſt let in motion by the immedia<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>e hand of the omnipotent Cre­ator; and are ſince continued in motion according to the ſimple laws of projectil<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> and centripetal force And as our ſureſt reaſoning in theſe things is by way of ana­logy, according to the known laws of nature, we muſt conclude that theſe M<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>teors are governed by the ſome general laws; and as all the <gap reason="illegible" resp="#PDCC" extent="1 word">
                  <desc>〈◊〉</desc>
               </gap> eſtial bodies, are ſo re­mote that they can have no ſenſible influence upon them, when they are within 100 miles of the ear<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>h, it is evident that he earth muſt be the attractive central body, round which they revolve; as the ſecondary planets revolve round the primary, or rather as comets revolve round the ſun in long elipſes, near to a parabol<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>.</p>
            <p n="7">VII. I SHALL therefore calculate the motion of theſe Terreſtrial Comets round the earth, on the ſame principles as D<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ctor Halley calculates the motion of comets round the ſun.</p>
            <p n="1">1. A BODY revolving in a circle, at the diſtance of 4000 miles from the centre, which is about 25 from the ſurface, will perform its revolution in 84 minutes. For as the cube of the moon's diſtance is to he ſquare of its periodical revolution in minutes, ſo is the cube of 4000 to the ſquare of 84′, which is 300 miles in a mi­nute: But if it revolves in an elipſes, near to a parabola, its velocity is aug­mented as 7 to 10, nearly, and will be 428 miles in a minute: The annual and di­<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>rna<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> motion of the earth may make a ſmali difference.</p>
            <p n="2">2. As the area of a circle 0,785 is to 84 minutes, ſo is 1<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>3d to 35′, the time in which at will deſcribe a q<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>adrant or a parabola, with the velocity of a circle.</p>
            <p n="3">3. As the ſquare root of 2 is to 1, ſo is 35 minutes, the time as in a circle, to 25′, the time as in a parabola. Therefore, the Meteor deſcribes a quadrant, or 100° of mean motion, in 25′, which is 4 degrees of mean motion, and 6° 6′ angular motion from the perihelion, in one minute. Upon theſe data I have calculated the following table of the motions of this Perreſtrial Comet. The firſt column contains the minutes of time before and after the perihe<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ion or perigee: The ſecond, the degrees of mean motion: The third, the degrees of angular motion: The fourth, its diſtance from the centre of the earth: And the fifth, its diſtance from the ſu<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>face of the earth, ſuppoſing its leaſt diſtance, at the perigee, is 25 miles: The ſixth, its motion from the perigee, in its orb<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ts, in miles.</p>
            <p>
               <table>
                  <row>
                     <cell role="LABEL">
                        <hi>Time.</hi>
                     </cell>
                     <cell role="LABEL">
                        <hi>Mean motton.</hi>
                     </cell>
                     <cell role="LABEL">
                        <hi>Ang. motton</hi>
                     </cell>
                     <cell role="LABEL">
                        <hi>Diſt. from cen<gap reason="illegible" resp="#PDCC" extent="1 letter">
                              <desc>•</desc>
                           </gap>
                        </hi>
                     </cell>
                     <cell role="LABEL">
                        <hi>Diſt. fr ſurf</hi>
                     </cell>
                     <cell role="LABEL">
                        <hi>Diſt. in orbit.</hi>
                     </cell>
                  </row>
                  <row>
                     <cell>0<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>
                     </cell>
                     <cell>0°</cell>
                     <cell>0° 0′</cell>
                     <cell>4,000</cell>
                     <cell>25</cell>
                     <cell>0</cell>
                  </row>
                  <row>
                     <cell>1</cell>
                     <cell>4</cell>
                     <cell>6 6</cell>
                     <cell>4,0<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>1</cell>
                     <cell>36</cell>
                     <cell>428</cell>
                  </row>
                  <row>
                     <cell>2</cell>
                     <cell>8</cell>
                     <cell>12 8</cell>
                     <cell>4,045</cell>
                     <cell>70</cell>
                     <cell>854</cell>
                  </row>
                  <row>
                     <cell>3</cell>
                     <cell>12</cell>
                     <cell>18 2</cell>
                     <cell>4,101</cell>
                     <cell>126</cell>
                     <cell>1,280</cell>
                  </row>
                  <row>
                     <cell>4</cell>
                     <cell>16</cell>
                     <cell>23 45</cell>
                     <cell>4,177</cell>
                     <cell>202</cell>
                     <cell>1,700</cell>
                  </row>
                  <row>
                     <cell>25</cell>
                     <cell>100</cell>
                     <cell>90 0</cell>
                     <cell>8,000</cell>
                     <cell>4,025</cell>
                     <cell> </cell>
                  </row>
                  <row>
                     <cell>lb. or 60</cell>
                     <cell>240</cell>
                     <cell>118</cell>
                     <cell>15,076</cell>
                     <cell> </cell>
                     <cell> </cell>
                  </row>
                  <row>
                     <cell>24h.</cell>
                     <cell>5760</cell>
                     <cell>160 58</cell>
                     <cell>140,2<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>0</cell>
                     <cell> </cell>
                     <cell> </cell>
                  </row>
               </table>
            </p>
            <p>To a perſon who ſtands at the perigee, at the diſtance of 428 miles, it will appear almoſt in the horizon.</p>
            <p>
               <pb n="12" facs="tcp:017113_0010_0FA02F51894F3978"/>
THIS calculation ſeems to anſwer exactly to all the apparent motions of theſe Ter­reſtria<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> Comets, and particularly that they appear firſt to be 50 or 100 miles diſtant from the earth, then, in their courſe, to come within 20 or 30 miles of it, and af­terwards are at a greater diſtance again; as may be clearly ſeen in the delineation annexed: It alſo ſeems to determine its real velocity with a greater preciſion than the moſt critical obſervations hitherto made: For, if it moves leſs than 300 miles in a minute, it muſt, in a little time, fall to the earth; and if it moves more than 428, it muſt go off in an hyperbola.</p>
            <p>THE preceding calculation is founded upon the known laws of motion, in which we cannot be miſtaken; but we have room for different conjectures about the num­ber and periodical revolutions of theſe Terreſtrial Comets; yet we are circumſcribed within certain limits. On the one hand we muſt not ſuppoſe that their number is ſo great, or that their periodical revolutions are ſo frequent, as to exceed obſervation: On the other hand we muſt not ſuppoſe that their periodical revolutions, and tranſ­verſe diameters, are ſo great, as that, in their a<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ogee, they would be in danger of being carried away, or greatly diſturbed in their motion, by the attraction of Venus, or any other coeleſtial body. It ſeems moſt natural to ſuppoſe, that there are more than one, and that their orbits are very differently ſituated, like thoſe of the ſorar Come<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>, in order to account for their different motions to all parts of the Heavens: Though, if we ſhould ſuppoſe that the<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>e is but one only, it ſeems poſſible that all theſe various mo<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ons might be accounted for, by the diurnal and annual motion of the earth, and the conſtant attraction of the moon, in its various longitudes and la­titudes, upon the Meteor, in the ſeveral parts of its orbi<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>; which muſt conſtantly change the ſituation of it, and may poſſibly, in length of time, carry its inclination, apogee and nodes, to every pa<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>t of the Heavens. B<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> the obſervations which have been made, it ſeems evident, that one has been ſeen in each country, oftener than on<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>e in 30 years. Upon the<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>u face of the terreſtrial globe, there are 1000 countries, each about 500 miles <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>quare; ſo that 30 of them may appear ſomewhere in the world within the comp<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> of a year, and yet <gap reason="illegible" resp="#PDCC" extent="1 span">
                  <desc>〈…〉</desc>
               </gap> ſeen in each particular country ſo often as once in 30 years. Let us, then, conjecture for the preſent, until we have farther light by more accurate obſervations, that there are 3 ſuch Comets revolving round the earth, whoſe mean diſtances are about as grea<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> a<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> 
               <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>he moon's, and, there­fore, performing about 30 revolutions in a year; then one of them will appear in ea<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>h country of 500 miles ſquare, once in 27 years: And ſo often, at leaſt, they have been in fact ſeen in Old England and New. This conjecture, I think, will full<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> ſolve all the various p<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>aenomena of <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>heſe Meteors which have hitherto been obſerved. And if their periodical revolutions are <gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ce in a month, they will loſe but little of their heat in their apogee, and ſo will be prepared to receive and emit a large quantity of fire when they come near the earth: Indeed, by their friction upon the a<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>moſphere, the<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap> will loſe near an hundredth part of their velocity, and ſo, in length of time, will be in danger of falling to the earth, ſooner than the planets are of falling to the ſun. But this may, in ſome meaſure, be p<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>evented, by the greater denſity and pr<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ſſure on the lower ſide— the exploſion towards the earth may cauſe it a little to recoil from it; —and a wiſe Providence may ſo order the ſituation of their orbits, as that once and a while the attraction of the moon, or ſome other heavenly body, may accelerate their motion and enlarge their orb<gap reason="illegible" resp="#PDCC" extent="1 letter">
                  <desc>•</desc>
               </gap>ts. As M. Whiſton ſup­poſes, the Comet, at the flood, accelerated the motion of the earth, and made its annual revolution 5 days and a quarter longer than it was before.</p>
            <p>
               <pb n="13" facs="tcp:017113_0011_0FA02F5232287FF8"/>
OUR obſervations have heretofore been ſo imperfect, as that we cannot eaſily de­termine minute circumſtances; but the general theory ſeems highly probable, if not certain, that theſe ſuperior Meteors are ſolid bodies, half a mile in diameter, re­volving round the earth in long elipſes, their leaſt diſtance being about 20 or 30 miles; that, by their friction upon the atmoſphere, they make a conſtant rumbling noiſe, and collect electrial fire; and, when they come neareſt to the earth, or a lit­tle after, being then overcharged, they make an exploſion as loud as a large cannon.</p>
            <p>I SHALL add one conjecture reſpecting the uſe and benefit of theſe Meteors.—It is poſſible that, by their violent exploſion and agitation, they may cleanſe and purify the air, and render it more ſalubrious to mankind; much more than thunder and lightning. There is an obſervation in the Phil. Tranſ. Abr. Vol. VIII, page 519, which ſeems much to favour this conjecture; it is in theſe words: <q>A Meteor was ſeen over England and Ireland, and at Venice, at the ſame time: It appeared like a great ball of fire, which burſt with an exploſion which ſhook great part of the iſland, and ſeemed to ſet the whole atmoſphere on fire. This Meteor put a<gap reason="illegible" resp="#PDCC" extent="1 letter">
                     <desc>•</desc>
                  </gap> end to the Catarrh and Diarrhea, and reſtored a general health.</q>
            </p>
            <figure/>
            <list>
               <item>The line A B, repreſents part of the earth's circumference.</item>
               <item>The line C D, repreſents the top of the atmoſphere.</item>
               <item>The line E F, repreſents part of the orbit of the Meteor.</item>
               <item>The figures 1 2 3, repreſent the diſtance of the Meteor, in minutes of time, from the perigee.</item>
            </list>
            <p>SCALE, 200 miles to an inch.</p>
            <p>If the leaſt diſtance of the Meteor from the earth, at the perigee, be 20 miles; then its diſtance from the perigee and from the earth in the ſeveral minutes and parts of a minute of time, from the perigee, will be as follows:
<table>
                  <row>
                     <cell>
                        <hi>Minutes &amp; parts of a<gap reason="illegible" resp="#PDCC" extent="1 letter">
                              <desc>•</desc>
                           </gap>m.</hi>
                     </cell>
                     <cell>0</cell>
                     <cell>1-4</cell>
                     <cell>1<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>
                     </cell>
                     <cell>3-4</cell>
                     <cell>1</cell>
                     <cell>1 1-4</cell>
                     <cell>1 1-2</cell>
                     <cell>1 3-4</cell>
                     <cell>2</cell>
                     <cell>2 1-4</cell>
                     <cell>2 1-2</cell>
                     <cell>2 3-4</cell>
                     <cell>3</cell>
                     <cell>3 1-4</cell>
                     <cell>3 1-<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>
                     </cell>
                     <cell>3<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>4</cell>
                     <cell>4</cell>
                  </row>
                  <row>
                     <cell>
                        <hi>Diſtance from pertgee.</hi>
                     </cell>
                     <cell>0</cell>
                     <cell>107</cell>
                     <cell>214</cell>
                     <cell>321</cell>
                     <cell>428</cell>
                     <cell>535</cell>
                     <cell>
                        <gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>42</cell>
                     <cell>748</cell>
                     <cell>8<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>4</cell>
                     <cell>960</cell>
                     <cell>1067</cell>
                     <cell>1174</cell>
                     <cell>1280</cell>
                     <cell>1385</cell>
                     <cell>1490</cell>
                     <cell>1595</cell>
                     <cell>1700</cell>
                  </row>
                  <row>
                     <cell>
                        <hi>Diſtance from earth.</hi>
                     </cell>
                     <cell>20</cell>
                     <cell>20,7</cell>
                     <cell>22,8</cell>
                     <cell>26,4</cell>
                     <cell>31,4</cell>
                     <cell>37,8</cell>
                     <cell>45,5</cell>
                     <cell>54,6</cell>
                     <cell>65,2</cell>
                     <cell>77,<gap reason="illegible" resp="#PDCC" extent="1 letter">
                           <desc>•</desc>
                        </gap>
                     </cell>
                     <cell>92,2</cell>
                     <cell>104,8</cell>
                     <cell>120,7</cell>
                     <cell>138,1</cell>
                     <cell>156,8</cell>
                     <cell>175,9</cell>
                     <cell>196,8</cell>
                  </row>
               </table>
            </p>
         </div>
      </body>
   </text>
</TEI>