thai the lens was imperfed and did no1 fulfill the conditions 

 of the order. Mr. (!. W. Ritchey has been instructed to proceed 

 at once to France and secure the casting of a perfeel disk at 

 the earliest lime possible. It is hoped thai this will be ac- 

 complished in a few months so thai the grinding and polishing 

 may be commenced by Spring. 



This work and the five small accessory mirrors with the 

 manufacture of the driving clock and the designs tor the 

 mounting, the steel dome and the building will he done by 

 .Mr. Ritchey and will require about three years. The cosl of 

 the optical parts will consume Mr. Hooker's Fifty thousand 

 Dollars and it is estimated thai the expense of the mounting, 

 dome and building will amoimi to several hundred thousands 

 of dollars. 



Telescopes serve the Astronomer in a two-fold manner: 

 First by their mighty [tower for gathering light. The un- 

 aided eye receives from an object as many rays as fall upon 

 the pupil, which, under normal conditions, is about one-fifth 

 of an inch in diameter. The object glass of a telescope serves 

 as a pupil of larger dimension, and as many rays as fall upon 

 it are carried to the retina id' the eye. The increase in light- 

 gathering capacity is in the ratio of the square of the diameter 

 of the object glass to the square of the diameter of the pupil 

 of the eye, and with an hundred-inch speculum, stars which 

 are beyond the vision, not only of the naked eye. hnt even 

 imperceptible through powerful telescopes, would become 

 visible. 



The second function of a telescope is to magnify the 

 image al Hie focus. Galileo's telescope brought Jupiter's 

 satellites 33 times nearer to his vision. It is difficult to slate 

 what magnifying power an hundred-inch mirror will allow, so 

 much depends upon the "seeing" in using light-gatherers of 

 large dimensions. A conservative estimate would probably 

 he from fifteen hundred to two thousand diameters. 



Wanted 



Any numbers of Volumes III. I V. V, and VI of the Bulletin, 

 particularly Numbers 4. (j and 8 of Volume 111. Number 5 of 

 Volume [V, and the Index of Volume V. 



We shall be greatly obliged to members who will send to 

 the Secretary any of these numbers, as they will enable him 



to complete sets which are ill demand. 



The whole of Volumes I Or II Will I"' cheerfully exchanged 



for No. (i of Volume III. or No. 5 of Volume IV. Send them 

 to the office of the Secretary. 625 San Fernando Building. 



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