HISTORICAL VIEW OP TnE

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writers have contended that it adds but little to hisreputation. Without disparaging his other exalted merits,we, however, regard this as constituting one of hisfairest claims to that immortality of fame with whichhe has been so justly invested.

Lenses, as we have already observed, were knownlong before this time, and used to assist vision; andhints, more or less obscure, may certainly be traced inthe records of earlier times of effects produced or ex-pected from combinations of lenses. After the announce-ment of the construction of the telescope by Galileo,several writers were not backward in ascribing the prin-ciple of it to others. These claims rest entirely onpassages the meaning of which is ambiguous. Fracas-toro and Baptista Porta have been named among theclaimants, as also Digges and De Dominis. Again,Jansen and Lipperliay, two Dutch spectacle-makers,contest the priority of having combined two lenses, sothat distant objects were seen through them magnifiedand inverted.

Galileo himself states that he had heard a rumour ofsuch a contrivance. He immediately applied himselfto consider, upon optical principles, in what way suchan effect could be produced; and at length constructeda telescope, which showed distant objects magnified anderect. He did not stop to investigate the subject in allits bearings, but, satisfied for the moment with thesuccess he had obtained, he eagerly proceeded to makefurther improvements upon the construction, and toenlarge the powers of the instrument, so as to render itavailable for the purposes of astronomy.*

The principle of the telescope and the microscopeare, to a mathematical optician, one and the same. Thetelescope is merely made to collect parallel rays fromdistant objects ; the microscope, diverging rays fromnear objects. The latter invention, therefore, couldhardly fail to follow immediately upon the former.Galileo constructed microscopes in 1612 ; bht he did

* The whole evidence is admirably discussed in Drinkwater’s Life ofGalileo, p. 2-t. See also a paper by prof. Moll., Roy. Inst. Journ. i. 319.