16 THE AMERICAN MONTHLY IMannarv, 



has also a fine selection of old instniinents, but both of them, like 

 Mr. Crisp, were unwilling to allow their treasures to be subjected 

 to tlie dangers of a long journey. The society will therefore be 

 conipelleil to fall back on the collection in the Army Medical Mu- 

 seum at Washington, wliich, it is hoped, the Government authori- 

 ties will bring here for exhibition. 



The exhibit of the society ougiit to be of a good deal of interest, 

 for in some senses it may be said that microscopy lias readied its 

 acme. Prot". Abbe says that it is not probable tliat any glass will 

 beiliscoyeredof higher refractive index than that kncnvn, and with- 

 out that it is not possible to construct lenses of much liigher power 

 or angle than at present. Our present objectiyes. tlicn, are nearly 

 perfected, unless future investigations show our theory of light to 

 be erroneous. In regard to microscope stands, there arc a large 

 number of forms for diHerent purposes, many very attractive. 

 Klonne & Mueller, of Berlin, manufacture one of the Zeiss form 

 wholly of aluminum, except the foot. Those who will exliibit, 

 so far as they have already consented, are Baker, Swift, Crouch, 

 Beck & Beck, and Powell of London, Klonne <!v: Mueller of Ber- 

 lin, Zeiss of Jena, Hartnack of Potsdam. Reichert of Vienna, 

 and proliably Nachet of Paris, and Leitz of Wet/lar. 



One of the pleasant features of the exhibit will be that, by ex- 

 press permission of the manufacturers, the committee of the so- 

 ciety w-ill be allowed to show the various stands and objectives 

 at the meetings of the society or at such times and places as may 

 be agreed on, so that all microscopists will have an opportunity of 

 seeing the best foreign work, and comparing it with that done in 

 this country. The domestic manufacturers will not be behind in 

 their display, and they have already taken the necessary steps to 

 be seen. Dr. E. Cutler, of New York city, has consented to 

 allow his famous Tolles 1-75 to be exhibited. The space assigned 

 to the society by Prof. Peabody, the chief of the department of 

 Liberal Arts, is in the south gallery of the Liberal Arts building, 

 next to the astronomical and photographic exhibits, and close to 

 the commercial displays of Bausch tS: Lomb, Qiieen & Co., Zeiss, 

 and others, and is in a very advantageous part of the building. 



Mosquitoes. — Petroleum has been found advantageous in pre- 

 venting the breeding of these insects. Four ounces in a pond 60 

 feet in area cleared it for 10 days. Creosote or any oil would 

 have the same effect probal:)ly. 



Mr. Howard, of the Agricultural Department, experimented 

 with kerosene upon a small area and killed 370 females. In 20 

 days these might have produced 74,000 young (200 each). It is 

 believed that this simple jjrocess of oiling the water of bogs and 

 ponds where they breed will greatly increase the value of lands 

 and of summer hotels near infested places. 



