Polytechnic Association. 5(35 



greater clearness of detail, and to increase the magnifying power at 

 the other -end of the microscope, that is, the eye-piece. With an 

 objective as high as a fifth, or even less, he uses a very deep eye-piece, 

 and to correct residuary aberrations of the objective, and at the same 

 time amplify, he introduces an important adjustable combination 

 between the eye-piece and the object glass. He claims to obtain 

 greater excellency, and with less cost than can be reached by using 

 very expensive high powers. A careful comparison of his instrument 

 with the best American and European microscopes should be made by 

 a competent committee, and the result of the test be reported to the 

 Microscopical Society. 



Dr. Van der Wey de — Whatever you can see with a weak eye- 

 piece, in a microscope, may be magnified by a stronger eye-piece, but 

 you cannot see any more. 



Prof. John Phin — The test employed in this case was forming 

 convex mirrors from small globules of mercury, and magnifying the 

 image. But there are tests so much more severe than this, that this 

 test is really worthless. I consider the old plan of magnifying by the 

 eye-piece perfectly useless. 



III. The Bat's Wing. 



Dr. Joseph Schobl, of Prague, has recently repeated the 

 experiments of Spallanzani, who, long ago, discovered that bats 

 which had their eyes put out were able, nevertheless, when allowed 

 to fly about in a room, to avoid threads stretched across it. 

 This faculty Spallanzani attributed to some highly developed sense 

 of touch possessed by the wing. Schobl covered the eyes of bats 

 with sticking-plaster, and after assuring himself that the bats were 

 guided by some other sense than sight, made a careful examination 

 of the structure of their wings. His researches have led him to 

 ascribe the phenomena to the power of peculiar nerve-endings in 

 the wing. Of the five layers of nerves, two are connected with 

 the Malpighian layer of the skin. To one of these, which is united 

 with every fine hair found on the upper and under surface of the 

 wing, he attributes a highly exalted sense of touch, and to the other 

 the appreciation of temperature, pain, etc. Dr. Schobl believes he 

 has discovered similar nerve-endings in peculiarly sensitive parts of 

 other mammals, an account of which will soon be published. 



Prof. Phin — A curious experiment of my own in the central 

 part of this State may be worth repeating. I was out fishing with 

 flies. Bats were quite numerous, and I wanted one for the purpose 



