ii6 THE MICROSCOPE. 



of far greater magnifying power than those at present remaining. 

 He was well acquainted with the method of viewing opaque objects, 

 which some years later (1740) was reproduced by Lieberkuhn. 

 Several authors make the mistake in stating that the magnifiers 

 used by him were globules of glass. Dr. Baker, to whom they were 

 referred for reports, distinctly asserts they were bi-convex lenses. 

 L., in letter to Roy. Soc, says that, from forty years' experience, he 

 prefers " microscopes of medium power, but of greatest degree of 

 perfection, as they are to be trusted." 



In 1665 Dr. Hooke published his Micrographia, and to him, in 

 i668, we are indebted for the substitution of glass globes for 

 lenses. He made lenses -^ diam. and polished them himself. 

 To him, too, we can trace the theory of the solar microscope, after- 

 wards described by Prof. Belthasaurs in Erlange, 17 10. Its prac- 

 tical execution was certainly due to Lieberkuhn, in Berlin, in 1740, 

 as we will see further on. Dr. Hooke was unfortunately constituted 

 in several directions. He was exceedingly jealous and very morose. 

 Ill health at various times interfered with the perfecting of several 

 of his important inventions or discoveries in time to anticipate the 

 fulfillment of the same work engaged in by others. This so incensed 

 the poor old man as almost to disqualify him for work at times. 

 Notwithstanding his failings and unpopularity, it is to him that we 

 owe much in the advancement of science in his day. Hooke, in 

 1678, makes the nearest approach in these early days to an immer- 

 sion lens when he says: "If you are desirous of obtaining a 

 microscope of one single refraction and consequently capable of 

 procuring the greatest clearness and brightness any one kind of 

 microscope is capable of, spread a little of the fluid you intend to 

 examine on a glass plate; bring this under one of your microscope 

 globules and move it gently upwards till the fluid touches the globule 

 dish; it will soon adhere, and so firmly as to bear being moved a 

 little backwards or forwards. By looking through the globule you 

 will then have a perfect view of the animalculae in the drop." — 

 Hooke s Lectures^ p. 98. 



It seems strange that so careful a compiler and historian as Dr. 

 Priestley should neglect accrediting Dr. Hooke with what was 

 truly due him, and still stranger when we think of them as country- 

 men. 



Pepy's Diary, 1664, says: "Comes Mr. Reeve with a micro- 



