i9o6] PICKERING— INTERNATIONAL SOUTHERN TELESCOPE. 49 



least double this sum, or $3,000,000. A sixth part of the last named 

 sum, or $500,000 would suffice to carry out the plan proposed in this 

 paper. Figures can be given with a good deal of confidence since, 

 at Harvard, we have had experience of a nearly similar character. 

 A reflecting telescope of two feet aperture and its mounting have 

 recently been constructed at a cost of less than $4,000. For a larger 

 telescope we may assume that the cost of drawings and plans will 

 be proportional to the first power, the cost of the machine- and hand- 

 work to the square, and of the material, to the cube of the dimen- 

 sions. At this rate, telescopes of six, seven, and eight feet aperture 

 would cost $42,900, $63,000, and $87,400, respectively. The five- 

 foot telescope at Harvard cost us much less than this rule would 

 imply, but the conditions under which it was acquired were excep- 

 tional. Assuming the cost to be proportional to the cube of the 

 dimensions, we have the cost in the three cases $108,000, $171,500, 

 and $256,000. The actual cost would probably lie between these 

 rather wide limits, but it is believed that a telescope of seven-feet 

 aperture and mounting could be constructed for $150,000. 



The current expenses can be closely estimated since, for seven- 

 teen years, the Harvard Observatory has conducted an auxiliary 

 observing station in South America. Ten thousand dollars a year 

 would be needed to carry on the proposed station satisfactorily. . To 

 produce this sum, allowing four per cent, interest, $250,000 would 

 be required. With the income, three or four assistants could be 

 maintained, who would keep the telescope at work throughout every 

 clear night, and perhaps some smaller instruments. A certain 

 amount of the income would be available for publication and for sub- 

 sidies paid to astronomers here or in other countries, for assistants 

 who would aid them in measuring and discussing the photographs. 

 Before the large telescope is completed the interest on the principal 

 would defray the expenses of th^ preliminary work of testing loca- 

 tions with smaller instruments, erecting houses for the observers and 

 similar work. If the fund had an independent foundation, an addi- 

 tional $100,000 would be required for an executive for the manage- 

 ment of the fund, etc. This would be saved if the superintendence 

 would be undertaken without charge by the Harvard or some other 

 existing observatory. The entire amount required would, there- 



PROC. AMER. PHIL. SOC, XLV. 182D, PRINTED JUNE 25, I906. 



