A uniial Report of iJte Council. liii 



constituent " (now called pearlite) he discovered a mineral, the 

 importance of which to mankind is still in this, the steel age, 

 imperfectly realised. His "intensely hard-constituent" is the 

 cementite of the modern metallographer. The pearly constituent 

 Dr. Sorby described thus: — "The optical characters of this 

 "substance led me to conclude that it had a very fine laminar 

 " structure before I was able to prove it by the use of high 

 "powers. It seems difificult, if not impossible, to explain its 

 " structure by supposing that it is an accidental mixture, whereas 

 " the facts are easily explained, if we suppose that it exists as a 

 "compound at a high tempeiature, and breaks up into a 

 " mixture on further cooling, as more iully described in my 

 " paper on the use of high powers. For this reason it will be 

 "convenient to retain the name, pearly constituent with the 

 " understanding that, as seen when cold, it is a mixture." 



In 1879, he commenced the study of marine biology on his 

 yacht " Glimpse," and that branch of science continued to 

 engage his attention very closely. "The reputation he had 

 gained as a student of the waters," says the Sheffield Telegraph, 

 "caused him to be nominated on the Royal Commission on 

 the Drainage of London in 1882. He had previously lived 

 on his yacht in the Thames, investigating the origin of the sand 

 bank at Crossness, but in connection with the important work 

 he did for the Royal Commission — the results of which are to 

 be found in two books of evidence given by him before the 

 ■Commission — he lived on his yacht 240 days, and spent seven 

 hours each day at his labours. The evidence he gave was 

 looked upon as of an exceedingly valuable character, and it 

 very considerably influenced the decisions of the Commission. 

 He went on in later years to investigate the causes of local 

 changes in the sea and rivers on the coasts, such as that in the 

 Isle of Thanet, where an important channel used by ships in 

 •early times, has been completely closed. Nearly all trace has 

 been removed of a stream, probably the so-called Ebbsfieet, 

 where the Saxons landed, and the important harbour of 

 Sandwich has been almost entirely destroyed." 



