274 THE AMEIUCAN MONTHLY [December, 



couraging predictions of high scientiiic authority that it was physically 

 impossible. My time this evening and your patience would not allow 

 of more than a hasty glance through its history. For the details, con- 

 sult the many well-filled booljs — I might say, libraries. As many as 

 500 works treating of the microscope and its employment can be found 

 in a single collection in this city. 



The history of the microscope prior to the year 1590 is fragmentary. 

 The question of antiquity of magnifying lenses has been thoroughly dis- 

 cussed. A large number of writers have, at various periods, been en- 

 gaged in the collection and examination of the works of ancient writers. 

 These, in turn, were compared and further elaborate research was con- 

 ducted as late as 1871 by M. T. H., Martin, who, in his conclusion, 

 remarks that magnifying lenses were not known to the ancients, or, at 

 least, were not used by them for any practical purpose. Mr. John 

 Mayall, of London, deceased but a few weeks since, who had devoted 

 many years of his life to the study of the history of the microscope, also 

 to a collection of ancient and modern instruments, remarks in his ex- 

 cellent series of lectures delivered before the Society of Arts, London, 

 in 1885, that his views agree in the main with those of Mr. Martin. 

 He came to the conclusion that the microscope, as we know it and em- 

 ploy it, is essentially an invention of miodern times, and to use his ex- 

 pression, " hit upon at a period corresponding almost marvellously 

 with the advent of the spirit of modern research, when the need of such 

 an instrument was, so to speak, mobt intensely felt by those precursors of 

 modern science who first struggled out of the meshes of the ancient em- 

 pirical methods into the free air of experimental methods." 



There are numerous instances cited of remote date, that many authors 

 are disposed to accept with historical significance, of the microscope. 

 Mention is made in Aristophanes' comedy, '• The Clouds," 431 B. C., 

 of the employment of burning glasses. Pliny mentions that physicians 

 cauterized by means of a globe of crystal. Alexander states that objects 

 may be ignited by heat of the sun passing through " a vase filled with 

 cold water." Similar statements are to be found in the works Philo- 

 pon. Seneca makes mention that " letters, though small and indis- 

 tinct, are seen enlai-ged and more distinct through a globe of glass 

 filled with water." 



Many passages could readily be quoted to show that the ancients 

 were awake to the effects of burning glasses, though the underlying 

 principles were not observed. 



Many remarkable and ridiculous anecdotes are recorded by the an- 

 cient writers concerning these early burning glasses. The burning of 

 the Roman fleet before Syracuse, 250 B. C, by means of polished 

 metal specula, shows that the attention of the ancients was directed to 

 the laws of light, but this and other grave and doubtful questions are 

 compared by the able historian before mentioned, Mr. Mayall, "to 

 that of our own Swift when he introduces us to the professor in the 

 Grand Academy of Lagodo engaged upon a project for extracting sun- 

 beams out of cucumbers, which were to be put in vials hermetically 

 sealed, and let out to warm the air in inclement summers." 



Before passing over the early records, which contain so many allu- 

 sions to glasses of this form, I should direct your attention to a piece of 

 rock crystal, " plano-convex," found by Mr. Layard at the excavations 



