270 PROCEEDINGS OF THE SOCIETY. 



A smaller Microscope was shown, which had an ingenious method 

 of attaching the outer tube of the sliding coarse adjustment to the limb ; 

 two holes were pierced through the front of the tube, so that the heads 

 of the screws fixing the tube to the limb might be on the inside of the 

 tube. This made a far more secure fitting than when the screws were 

 put in from the other side. 



The last was a very small compound Microscope, whose total height 

 was only about 3 in. 



The next Microscope was sent for exhibition by Mr. Ernest Barker. 

 It was of the portable kind, and was attached to its box, which measured 

 only 4^ X 1| X 2 in., and which also contained a small live-box, a 

 pipette, a pair of tweezers, and a trough. It was a very compact and 

 portable little instrument, eminently suitable for held work. 



The Chairman said they were greatly obliged to the various ex- 

 hibitors of these Microscopes, and also to Mr. Nelson for kindly explain- 

 ing them. The last one referred to was certainly a most ingenious and 

 compact little instrument, and likely to be extremely useful as a travel- 

 ling Microscope to persons in India or other places where perhaps 

 transport was difficult, and every additional ounce added to the burden 

 to be carried was of importance. The only inconvenience appeared to 

 be that it could not be used upright, which was rather necessary when 

 the object was in liquid. 



The thanks of the Society were cordially voted to Mr. Nelson and 

 to those gentlemen who had sent the various instruments for exhibition. 



Mr. E. M. Nelson read the following extract, kindly sent by 

 Mr. W. Jerome Harrison, of Birmingham, from Dr. Hooke's Micro- 

 scopium (1678), describing a method of using some convex lenses by 

 contact with a drop of water. 



1678.— Hooke, Kobt., Lectures and Collections: Part II. Micro- 

 scopium : containing . . . the Author's Discourse and Description of 

 Microscopes, improved for discerning the nature and texture of Bodies. 

 8vo, London. 



Pp. 98-99.— Objects may be placed between two glass plates for 

 examination. Globules of melted glass fixed in metal plates make good 

 high-power lenses. " If further, you would have a Microscope with one 

 single refraction, and consequently capable of the greatest clearness and 

 brightness that any one kind of Microscope can possibly be imagined 

 susceptible of, when you have fixed one of these little globules as I 

 have directed, and spread a little of the liquor upon a piece of looking- 

 glass plate, then apply the said plate with the liquor next to the globule, 

 and gently move it close to the globule, till the liquor touch; which 

 done, you will find the liquor presently to adhere to the globule, and 

 still to adhere to it though you move it back a little ; by which means, 

 this being of a specifique refraction, not, much differing from glass, the 

 second refract on is quite taken off, and little or none left but that of 

 the convex side of the globule next the eye ; by which means as much 

 of the inconvenience of refraction as is possible is removed, and that 

 by the easiest and most practicable expedient that can be desired." 



He thought it was extremely interesting to know that the immersion 



