VOL. LV.] PHILOSOPHICAL TKANSACTIONS. 245 



XXFIIT. Extracts of three Letters of Sir F. H. Eyles Stiles, F. R. S. concern- 

 ing some new Microscopes made at Naples, by J. M. di Torre, and their Use 

 in viewing the Smallest Objects. Dated Naples, 1761. p. 246. 



The diameters of the glasses, sent to the r. s. and their magnifying powers, 

 are as follow. 



Glass. Diameter. Magnifying powers. 



1 St, Near two Paris points, 640 times, and upwards, in diameter. 



2d, One Paris point, 1280 



3d, One Paris point, 1280 



4th, Haifa Paris point, 2560 



These glasses are so small, that the diameter of the highest magnifier among 

 them is but half a Paris point, which is no more than -j--^ of an inch, the 

 point being ^ of a line, and the line -^ of an inch. The great difficulty with 

 respect to these glasses, consists in the handling them, and getting them into 

 the little brass sockets prepare?! for their reception. The making them in his 

 method is soon done; but they must be socketed before he can examine to see 

 whether the flame of his lamp, which produces them, has succeeded to the per- 

 fection he wished; that is, whether they be perfectly spherical, and without flaw, 

 speck, or other accident, which they are so liable to, that he makes many 

 before he produces one to his mind: and indeed he sets so little value on them, 

 till he has proved them by the vision of some object, that if one of them, when 

 he has made it, slips out of his little pincers before it has been proved, if he 

 cannot recover it at once, he often makes a new one, rather than give himself 

 the trouble to search for it. This high magnifier increases the object 256o 

 times in diameter; it is the first and only one he has ever succeeded to make of 

 that high power; so that this present is a curious one. 



j4n Account of some Microscopic Observations on the Human Blood. 



The first observation was made July 2d, 1761, with Wilson's single micros- 

 cope, constructed for a perpendicular inspection, with a mirror beneath it for 

 reflecting the light. The instrument was placed on a table near a south window, 

 but the sun's rays were not reflected on the object; it being Father di Torre's 

 opinion, that the ordinary day-light would show the globules in a more natural 



plication was fine sea salt, which was plentifully sprinkled and rubbed in and about the wound and 

 scarification. These were done in the space of about 2 minutes after the wound was mad''.. Then 

 a poultice made of burdock-root pounded, and mixed with a large portion of sea salt, was applied 

 to the wound, and another of blood-root was bound about his leg a little below the knee. In the 

 mean time, the patient took inwardly saffron and water, in which was steeped the bark of white 

 ash, which caused him to vomit. The consequence of the wound was a tumefaction, which was 

 greatest in the foot, but extended to the knee, where it ended. After these applications, nothing 

 remarkable was observed in the wound. They were continued for 2 days, and the patient perfectly 

 cured. Mr. Strong supposed the salt to be the principal ingredient, which effected the cure.— Orig. 



