CHAP. VII.] FELLOW OF TRINITY. 221 



I was talking to Willis about the platometer, and he 

 thinks it will work. Instead of toothed wheels to keep the 

 spheres in position always, I think watch-spring bands would 

 be better. 



Trin. Cell, 25th November 1855. 



I think I told you that Pomeroy was ill. He has had 

 rather a sharp attack of bilious fever. His mother has come 

 up. He was getting round on Thursday, but he saw too 

 many people, and was rather the worse of it. However, the 

 doctor says that the recovery simply requires attention, and 

 patience, and no hurrying. 



I have been reading old books of optics, and find many 

 things in them far better than what is new. The foreign 

 mathematicians are discovering for themselves methods which 

 were well known at Cambridge in 1720, but are now 

 forgotten. 



I have got a contrivance made for expounding instru- 

 ments. It is a squared rod, one yard long, on which slide 

 pieces, which will carry lenses. Each piece has a wedge 

 which fixes it tight on the rod, and a saw-shaft, with 

 holes through it, for fastening the pasteboard frame of 

 the lens. By means of this I intend to set up all kinds 

 of models of instruments. 



To E. B. LITCHFIELD, Esq. 



Trin. Coll., 28th November 1855. 



I am busy with questionists pretty regularly just now, 

 slanging them one after another for the same things. As 

 they have just set upon me for the evening, I must stop now 

 and get out some optical things to show them. 



To HIS FATHER. 



Trin. Coll, 3d December 1855. 



I had four questionist papers last week, as my subjects 

 come thick there ; so 1 am full of men looking over papers. 

 I have also to get ready a paper on Faraday's Lines of Force 

 for next Monday. 



