Kansas Academy of Science. 19 



luminous shadow formed by but not a part of the comet. In 1807, and again 

 in 1811, Chladni, a careful observer, noticed what he styled a prodigious 

 ebullition proceeding from the nucleus to the extremity of the tail of a comet, 

 in a few seconds of time. The tail of the comet of 1811 was estimated to 

 extend four millions of leagues, and light itself travels no faster. It was as 

 if the waves of ether were made visible in their undulations. 



A few words with regard to the resistance of a medium, and I close. Only 

 the orbits of short-period comets have been determined with any approach 

 to accuracy; and of these, Encke's has the least perihelion distance. This 

 comet, too, has a shortening of its period, apparently in consequence of the 

 resistance of the medium through which it passes. Is it not probable, too, 

 that such a resistance is the explanation of some of the irregularities of the 

 comets of long period? Thus the comet of 1264 and 1556 was expected to 

 return in 1848. May it not be that the comet of 1843 was the identical one 

 with its period shortened? The comet of 1843 passed very near the sun; 

 nearer even than Encke's comet. Arago made a study of the records of 

 Halley's comet, to determine if possible whether in its successive reappear- 

 ances it had lost any of its brilliancy. He thought it had lost nothing. May 

 not this again be due to the probable fact that in successive returns the comet 

 approaches nearer the sun, encounters more and more of the resistance of the 

 medium, and therefore tends to develoj) more fully the phenomena of the 

 tail, which would otherwise be less developed, because the nucleus must be 

 losing some of its volatile elements? 



Thus questions of interest press upon us, and astronomy, though the oldest 

 of the sciences, is ever opening new and attractive fields of study. 



METEOKOLOGICAL SUMMARY FOE THE YEAR 1873. 



PROF. F. H. snow's ANNUAL, REPORT AS METEOROLOGIST TO THE STATE BOARD OF 



AGRICULTURE. 



Station, Lawrence, Kansas. Latitude 38°, 58'; longitude 95°, 16'. Elevation of barometer and ther- 

 mometers, 884 feet above the sea level and 14 feet above the ground; rain gauge on the ground; 

 anemometer 105 feet aljove the ground, on the dome of the University building. 



TEMPERATURE. 



Mean temperature of the year 52.71°, which is 0.17° lower than the mean 

 temperature of the five preceding years. Notwithstanding this very near 

 approximation of the mean yearly temperature to the mean of past years, 

 the range of temperature was much greater than in any previous year of our 

 record, amounting to 130°. The extremes were 26° below zero January 29, 



