The Cooke 25 inch telescope is used to look at Jupiter's moon Amalthea

 On January 24^th and February 4^th 1893 Mr Newall using the 25 inch Thomas Cooke & Sons telescope at the new observatory at Cambridge observed the 5^thsatellite of Jupiter.

(I assume by the 5^thsatellite he means Amalthea which was discovered by Barnard in 1892)

Mr Newall remarked that it has been most justly described as a very difficult object to see.