NOTES ON SOME CELESTIAL PHOTOGRAPHS. 93 



For purposes of comparison I append particulars of the weights 



of rabbits arriving from the bush, well-fed and in healthy con- 

 dition : — 



1 Kilog. 340 gram. ... about ... 2 lbs. 14 ozs. 



1 „ 600 „ ... „ ... 3 lbs. 7 ozs. 



1 „ 200 „ ... „ ... 2 lbs. 10 ozs. 



1 „ 700 „ ... „ ... 3 lbs. 11 ozs. 



NOTES ON SOME CELESTIAL PHOTOGRAPHS 

 RECENTLY TAKEN AT THE SYDNEY OBSERVATORY. 



By H. C. Russell, b.a., c.m.gl, f.r.s. 



[Read before the Royal Society of N.8. Wales, September 2, 1891.'] 



In order to complete our photographic apparatus, it was necessary 

 to obtain such an attachment to the Star Camera, as would serve 

 to record highly magnified images of double stars, the moon and 

 other objects. This has recently been added, so that now we can 

 record double stars photographically on a scale which gives ample 

 dimensions for accurate measurement, viz., thirty-six inches to 

 one degree, or 0*01 inch equal one second of arc. It will be 

 remembered that the enlarging lens mentioned by me in June last 

 made the scale ten inches to one degree, and gave a result as large 

 as a direct photograph in a telescope forty-seven feet long, but the 

 new one makes the telescope, so far as the magnifying power is 

 concerned, one hundred and seventy-nine feet long ; on a favour- 

 able night one would with this get a picture of the moon twenty 

 inches in diameter. We have taken portions of the moon upon 

 this scale, and I think you will agree with me when I say that 

 these photographs are finer than anything which has been done, 



