1891.] MICIlOSCOriCAL JOUllNAL. 275 



of Sargon'h palace, Niniroud. This lens is oval, about one ami one-half 

 inches long, one inch broad, and three-sixteenths of an inch thick. 

 Tliis Assyrian •' lens" is now in the collection of the British Museum, 

 and bears date of 721-705 B. C. 



Authorities ditler in opinion as to the possibility of this being a lens, 

 or more particularly as to its employment as such. Brewster, after 

 critical examination, states that it condenses light, and that it has a focus 

 of about four and one-half inches. The probable date of this lens is 

 fixed by the authorities of the British Museum by the objects found 

 with it. 



This Museum contains, also, two antique bosses to which are assigned 

 the period of " not later than 270-260 B. C." But we will pass beyond 

 this early history of optics involved in considerable obscurity, and call 

 your attention to a more authentic period. 



The first instrument to v/hich I wish to draw your attention is the 

 first compound microscope, made in Middleburg, Netherlands. It 

 consists only of two convex lenses, and was made by Hans or Zacha- 

 rias Janssen in 1590. There is a letter written by W'^illiam Boreel, 

 Dutch Ambassador in France, stating that Hans and Zacharias Janssen, 

 whom he knew perfectly well, having been their neighbor at Middle- 

 burg, and having often played with them when they were young, he 

 says in that letter that compound microscopes were made by the Jans- 

 sens long before the year 1610. 



About 1866 an old microscope was found at Middleburg. It was 

 exhibited at the South Kensington Loan Collection in 1876. Harting 

 (an author and historian of the microscope), after-examining the orig- 

 inal, came to the conclusion that it was really made by Janssen. In 

 1876, when the original was exhibited at the Loan Exhibition, Mr. 

 Crisp had a copy of it made, and in 1884 Mr. Mayall had a copy made 

 after Mr. Crisp's copy for the collection in the Army Medical Museum 

 in this city. 



In 1891, shortly before his death, Mr. Mayall went to Middleburg in 

 person and examined the original, became dissatisfied with the accu- 

 racy of the reproduction, and had four reproductions made under his 

 eye ; one to replace the copy in the Army Medical Museum. 



The original was presented to the '' Zeeuvvsch Genootschap der 

 Wetenschappen," and from that time was so unknown, even in Hol- 

 land, that it is not mentioned in such a complete history of the micro- 

 .sc'ope as that of Harting. (Geschichte und gegenwiirtiger Zustand des 

 Mikroscopes, Braunschweig, 1866.) The magnifying power obtaina- 

 ble with the instrument is not great. 



The Italians have made great etibrts to give to their nation the credit 

 of inventing the microscope, but it is now clearly shown and accepted 

 tliat the Janssens made the fiist microscope at Middlcluirg. Holland, 

 about 1590 or 1591. 



Galileo, from the testimony of himself, states that the instrument was 

 of Dutch origin, and of date anterior to his own production of the tele- 

 scope, 1609. 



Much interest was shown about the i6th centuVy in the efiects pro- 

 duced by varying the position of lenses, and after the first invention 

 there followed a goodly train of makers. Galileo, 1637 ' Divini, 1657, 

 and Campani, ante 1665 ; Hooke, 1665 ; Cherubin d'Orleans, 1671 ; 



