334 ANNUAL OF SCIENTIFIC DISCOVERY. 



descending ether, so as to present double and multiple tails ; that twice 

 in the year, in August and November, the earth plunges through the 

 sheet of warm ether, causing a warm period in each month, the dog 

 days and the Indian summer ; and that in the middle of these two 

 periods it causes the return of the August and November meteors. 



Shute on the Companion of Sirius M. Shute's observations on 

 the satellite of Sirius, published during the past year, seem to support 

 the views of Mr. Safford of Cambridge, Mass, viz : that there is no 

 physical connection between the two stars. 



'Distance of Sirius. M. Flammarion, in the Cosmos, speaking 

 of this magnificent star says : " thanks to the labors of Sir John Her- 

 schel, we know that the absolute intensity of the light of Sirius has 

 been estimated at 224 times that of the sun, and that its parallax, 

 amounting to 0"'23, gives for its distance from the earth the probable 

 number of 52,000,000,000 of leagues. It follows that we do not see 

 the Sirius of to-day, but of 22 years ago ; the ray of light that we 

 receive to-day having been emitted by the star about 1840." 



Comparing the Light of Stars. In Comptes Rendns for the llth 

 of April, 1864, M. Chacornac describes a method of mounting a plane 

 mirror so as to bring into the field of a telescope the image of one stars 

 while the telescope receives directly the light of another. By this 

 means the two images are brought into simultaneous view, the one of 

 course less brilliant than it should be, through loss of light in reflec- 

 tion. He gives the calculations necessary to work out the comparison. 

 Sirius he finds to be five times as bright as Arcturus. He is able to 

 work by this method upon stars from 20 to 160 apart. When seen 

 simultaneously, Arcturus looks orange red, and Sirius has a slight 

 green tint. 



WHAT IS KNOWN ABOUT SHOOTING-STARS. 



Of shooting-stars there is an average of from five to seven visible 

 every hour on a clear night. They are stray visitants in contradis- 

 tinction to the prodigious swarms of November and August, which 

 observation during twenty-five years has decided to be accurately return- 

 ing phenomena. Arago gives a summary of the times in each month 

 when mete jrs are chiefly seen ; it is as follows : January. Shooting- 

 stars are rare, 1st, to 4th, if at all. February. The ancient showers 

 of meteors announced for this month by the chroniclers seem to have 

 failed for the last eight or nine centuries. March. Occasionally. 

 April. From 4th to llth, and 17th to 20th. May. Shooting-stars 

 are rare. June. Shooting-stars are very rare. July. The appari- 

 tion of showers begins now to increase in number ; we may expect 

 them about July 26th to 29th. August. The well known period of 9th 

 to llth. September. Rare but possible from 18th to 25th. October. 

 In the mid lie of the month. November. As usual from llth to 

 13th, though less abundant. December. About 5th to 15th. 



From this it will be seen that shooting-stars are much more numerous 

 during the latter half of the year, when the earth is passing from sum- 

 mer to winter, or, in astronomical phraseology, from aphelion to peri- 

 helion. The same increase of number in the last six months of the 

 year is observable in the appearance and fall of fire-balls and aerolites. 

 Now by what theory can we account for this uniform return of meteors 

 in each year ? 



