130 Britain's Heritage of Science 



graduated as fifth wrangler in 1826, and was elected to the 

 Professorship of Mineralogy three years later. The mathe- 

 matical knowledge he had acquired fitted him peculiarly to 

 deal successfully with that branch of his subject to which he 

 mainly devoted himself. He developed a new system of 

 crystallography, which rapidly gained acceptance owing to 

 its simplicity and mathematical symmetry. Miller also took 

 a great interest in primary standards, and had a large share 

 in the reconstruction of the standards of length and weight, 

 in 1839, after their destruction in the fire which broke out in 

 the Houses of Parliament. 



We must postpone considering the achievements of a 

 younger generation of Cambridge men, including John 

 Hopkinson, George Darwin, John Poynting and others, 

 until the earlier work of other seats of learning has been 

 dealt with. 



The Scotch Universities claim our first attention. At 

 the beginning of the nineteenth century Thomas Charles 

 Hope (1766-1844) enjoyed an unrivalled reputation as a 

 teacher. It is recorded that in 1823 he lectured to a class of 

 575 students. At the age of twenty-one he was appointed 

 Professor of Chemistry at Glasgow, but resigned soon after 

 to become Assistant Professor of Medicine. In 1795 he 

 settled down at Edinburgh, as joint Professor of Chemistry 

 with Joseph Black, becoming sole Professor of the subject at 

 the latter 's death in 1799. Hope discovered the important 

 fact that within a certain range of temperature just above 

 the freezing point, water does not behave like ordinary 

 substances, expanding when the temperature is raised, but 

 contracts, reaching a point of maximum density near 4 C, 

 This is a matter of considerable importance in the economy 

 of nature, for when in the cold of winter the temperature 

 of a sheet of water sinks below the critical point, the colder 

 water is also the lighter. Hence ice first appears as a thin 

 layer on the surface, while the main body can be in stable 

 equilibrium below at a temperature higher than the freezing 

 point. But before the ice can form at all, the whole mass 

 must have cooled down below 4 C. Hope also had an 

 important share in the discovery of the element strontium. 

 A mineral discovered at Strontian in Argyllshire in 1787 



