Before proceeding to narrate some of the marvelous trans- 

 formations which his sensitive films recorded, ii may be well to 

 state certain theories now held regarding the formation of a 

 comet's tail. The researches <>l Arrhenius and the experiments 

 of Nichols show thai the repulsive force which drives the 

 exceedingly minute particles from the cornel is due to the 

 pressure of Light — the impact of the sun's rays. These Infini- 

 tesimal particles, though so numerous as to form ;i gossamer 

 trail of light behind the comet, are yet of such extreme tenuity 

 thai faint stars can be seen through clouds of them which are 

 thousands of miles in thickness. Bu1 these trails of lighl are 

 subjed to remarkable distortions, deflections and curvatures 

 in form, and also to sudden and frequenl changes in brilliancy, 

 probabh due to other causes than lighl pressure, perhaps 

 electrical. 



As an example of the capricious behavior of the Morehouse 

 comet, on the 14lh and 15th of October it was faintly visible 

 to the naked eye: on the 17th it was not thus visible; hut in 

 the latter part of the month it grew so brighl that on the 29th 

 it was pronounced very conspicuous, villi a tail which could 

 be 1 raced for five or six degrees. On the very next night, 

 October 30th, it was comparatively faint. 



< »n the 14th of October, Mr. Miller at Swarthmore, making 

 telescopic observations, noticed two condensations or luminous 

 masses in the tail. On the following nighl tie i Mind thai they 

 had been moving rapidly from the comet's head. In the c mis,' 

 o| twit and a half hours one of these condensations moved 

 224. ikiii miles, and the other 247.000 miles. A comparison of 

 positions for twenty-four hours showed that their average 

 velocity was 129,000 and 142.000 miles per hour, respectively. 



On the 30th of September, while Director Wilson of the 

 Goodsell Observatory was photographing the comet, its tail, 

 then telescopically eigh! decrees in length, apparently 

 detached itself from the head. On the next nighl the brighl 

 portion oi the tail was two degrees from the comet's head. 

 showing a rapid movement of the luminous mass during the 

 previous twenty-four hours. 



Another account mentions a similar occurrence, a narrow 

 streamer ran ou1 from directly behind the nucleus, ami this 

 was barely visible in the telescope, hut aboul 45 minutes 

 (three-fourths of a degree) from the head, the tail suddenly 

 brightened and broadened out to a width of 20 minutes, and 

 from this point broadened out still more and curved to the 

 rearward of the comet's motion. These rapid transformations 

 of the tail have not been paralleled in comet observations 

 hitherto. They form interesting studies which are calculated 

 to throw much lighl on the nature and constitution of these 

 strange heavenly bodies. 



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