352 
MINUTES OF PROCEEDINGS OF 
A detailed agreement was accordingly drawn out with him, in the 
preparation of which the Sub-Committee was most ably assisted by 
Warren De La Rue, Esq., V.P.R.S., who further permitted them to 
insert a clause providing that no part of the price of the telescope 
was to be paid until the instrument was examined and passed by him. 
The telescope was to have been finished by the end of August, 1872, 
but various causes prevented its being actually mounted in its place in 
the Observatory until the end of December in that year. 
One of the causes of delay is noteworthy, as it appears not to have 
been encountered before—viz., variation in the performance of the 
object-glass, caused by variations of temperature, and traceable to the 
constitution of the material. The process of re-annealling the glass 
having been tried without effect, a new glass had to be obtained from 
the makers—Messrs. Chance, of Birmingham. 
As in July, 1872, the telescope was all finished with the exception of 
the object-glass, permission was given to Mr. Grubb to bring it over 
from Dublin, and proceed with its erection. It was then discovered 
that the base upon which the pier of the telescope was to rest, was in 
contact with the floor of the equatorial room, and was also unsafe. 
The old stones forming the upper surface of the base were taken away, 
and a fine block of granite—obtained from the Dockyard by the 
courtesy of the Royal Engineer Department—was laid in their place. 
The work, which demanded much skill and patience for its execution, 
was admirably performed by a squad of gunners, under the immediate 
direction of Major Betty, R.A. 
The new object-glass being finished, and all other preparations being 
completed, the telescope was put together in its place in the last days 
of November, 1872, by Mr. Grubb ; but the weather continued for-many 
weeks most unfavourable for observations. 
On the 4th of February, 1873, Mr. De La Rue was able to give the 
instrument a preliminary examination. ITe pronounced most favourably 
on its construction generally, but noted some small mechanical defects 
which it would be desirable to rectify before testing its optical qualities. 
His remarks were communicated to Mr. Grubb, by whom they have 
been acted on, and the telescope may be said to be now quite complete. 
There now only remains to test the object-glass. 
The state of the weather, and Mr. De La Rue's indisposition, have 
prevented hitherto any real judgment on this point. Pending its 
determination, which the Sub-Committee is sanguine will prove highly 
satisfactory, and in recognition of the ingenuity and skill evinced by 
Mr. Grubb in the construction of the instrument, the Secretary w r as 
authorised to pay him, on account,- £250. 
In now handing over the telescope to the Committee, R.A. Institu¬ 
tion, the Sub-Committee begs to express its sense of the forbearance 
of the members at the delay in the accomplishment of its task. To the 
interruptions inseparable from the construction of an instrument so 
accurate and complicated, have been added the special causes of delay 
stated above. The Sub-Committee, while it has never ceased to urge 
on the progress of the work, has kept in mind, as of primary importance, 
the excellence of the instrument. 
