Norman Macleod Ferrers. 275 



thought, unduly. The taxation of the Colleges had to be faced. 

 Ferrers urged that this should be effected by a percentage on the 

 divisible revenues of each College, but the Commissioners insisted on 

 the principle of raising a fixed annual sum from the Colleges collec- 

 tively. This sum began at 5,203 in 1883 and rose gradually to over 

 25,000 in 1902. 



As a consequence of his position as Tutor and Lecturer, Ferrers 

 was necessarily much employed in examinations. The standard of the 

 papers set in Caius College, under his superintendence, was considered 

 to be high, so that it was generally worth while for a student to 

 consult them as a source of good questions from which something out 

 of the common could be learnt. He was Moderator or Examiner 

 eleven times, more times he believed than any one else recorded in 

 University history. 



His first book was called " Solutions of the Cambridge Senate House 

 Problems for the Four Years, 1848 1851." In this he was assisted 

 as joint author by J. S. Jackson, another Caius man and fifth wrangler 

 in his own year. 



Ferrers was also the author of a treatise on " Trilinear Co-ordinates," 

 published in 1861. These co-ordinates seem first to have been 

 brought into notice in the University by some chapters in " Salmon's 

 Conies," but there was no regular treatise on the subject. Ferrers 

 book at once became one of the text-books much used for the 

 Tripos examination. There was a second edition in 1866, and a 

 third in 1876. The subject is, however, not now studied to the same 

 extent. 



At the request of the Master and Fellows of Caius College, Ferrers 

 edited the " Mathematical Writings of George Green," a man of con- 

 summate genius who was fourth wrangler in 1837, and afterwards 

 Fellow of his own College. This important work was published in 

 1871, and rendered generally accessible a series of memoirs which 

 have remained of fundamental importance in both pure and applied 

 mathematics. These writings have also a special interest as the work 

 of an almost untaught mathematician ; a glance at the contents of 

 the volume shows how much of the after progress of discovery had 

 been anticipated by him, or has its roots in his work. 



His treatise on "Spherical Harmonics," published in 1877, presented 

 many original features. The theory of ellipsoidal harmonics was 

 first studied by Green and Lame, who used different methods. In his 

 last chapter Ferrers gives an account of these functions, using both 

 methods and adding things of his own. He also illustrates their 

 application by the problem of the attraction of a heterogeneous 

 ellipsoid. 



One of his early memoirs was on Sylvester's development of 



