TWENTY-SIXTH CONGRESS, 1839-1841. 213 



The visitors are required to make a report once a year to the senate of the 

 university. 



In instituting a new observatory it appears to me very desirable that there should 

 be appointed a body like the board of visitors at Greenwich and at Cambridge, with 

 power to require reports from the astronomer and perhaps to direct him in some 

 degree, and with the duty of reporting to the governing body. 



The visitors of the Cambridge Observatory are all members of the senate of the uni- 

 versity. The visitors of the Greenwich Observatory are persons living in different 

 parts of England. 



6. At Cambridge Observatory there are two assistants and a laborer. 

 At the Cape of Good Hope the same. 



At Edinburgh, Dublin, and Armagh, I believe, one assistant each. 

 Their duties are to observe and to calculate, under the direction of the astronomer. 

 The salaries of the Cambridge assistants are, I think, 80 each per annum, with 

 apartments. 



7. The instruments at Cambridge Observatory are: 



A mural circle, 8 feet in diameter, made by Troughton; price, 1,050. 



A transit instrument, 10 feet long, made by Dolland; price, I believe, 600. 



An equatorial 5-foot telescope, made by Jones; price, about 750 (many complaints 

 of this price) . 



Several small instruments, telescopes, etc. 



Three clocks; one cost 100 to 120. 



A 20-foot telescope, presented by the Duke of Northumberland. 



At Oxford there are some quadrants, not used; and also a circle, 4 feet diameter, 

 made by Jones; and an old transit. 



At Edinburgh: A mural circle, 4 feet in diameter, made by Simms; and a transit, 

 made by Repsold, of Hamburg. 



At Armagh: A mural circle, 4 feet in diameter, made by Jones; and a transit 

 (maker not known) . 



At Dublin: An altitude and azimuth instrument; the vertical circle, 8 feet in diam- 

 eter, made by Ramsden; and a transit. 



I may remark that, in the construction of instruments, expense may frequently be 

 avoided by leaving some points to the discretion of the instrument maker. As 

 an instance: When I superintended the equatorial mounting of the 20-foot telescope 

 at Cambridge I found occasion for a 5-foot circle, and I directed it to be cast in, one 

 piece of bell metal. It appears to answer perfectly well. Mr. Simms is quite satis- 

 fied with it, and thinks it possible that it might be made, at still less expense, of 

 cast iron. Since that time Mr. Simms has had, I believe, two orders for large cir- 

 cles; and when I have urged him to have each cast in one piece he has expressed 

 his wish to do so; but has informed me that his orders were to make them "like the 

 Greenwich circles," and has therefore considered himself compelled to put them 

 together in many pieces, in the same way as the Greenwich circles, at much greater 

 expense than would have been implied in the construction mentioned above. 



G. B. AIRY. 



JUNE 8, 1839. 



Since writing the answers above, I have received from Mr. Simms the following 

 list of prices: 



The mural circles for Greenwich, Cracow, Brussels, Edinburgh, and Lucknow, are 

 all of the same dimensions (6 feet in diameter) , and were all made by Troughton. 

 The price in each case was 735. Mr. Simms states at this price there was no profit 

 (Troughton was wholly regardless of profit in constructing these instruments) , and 

 that he would not like to undertake one for less than 900. 



Thi> mural circle for Cambridge, 8 feet in diameter, was made by Troughton for 

 1,050. 



