Dr. Rich exhibited six microscopes, a Beck grand binocular, a Zentmayer grand, a Curtis mounting microscope, two Wales & Hawkins improved, and a Beck "popular". Special mention must be made of Dr. E. Curtis' invention, which, in regard to convenience of use, originality of design, and capability of diverse applications, stands foremost. It is undoubtedly the best dissecting microscope, it may be used as a binocular, and is simple as well as compound. The stage and illuminator are not attached to the microscope, but consist of an oblong rectangular box which stands on the table under the objective lens, and the whole arrangement is evidently the result of the experience of a hard-working professional microscopist. Dr. Rich exhibited under these instruments most beautiful specimens of the wing cover of the West Indian beetle, and also some remarkable arrangements of diatoms, first produced several years ago by a lady in London. They were, for a long time, a profound mystery, until the German scientist, Möller, in Holstein, produced them for the trade. The diatoms are on slides containing 100, 400 or 600 specimens each, all classified in species according to an accompanying catalogue.
Among the appendages shown was the improved section cutter of Dr. E. Curtis, in which the knife is enclosed in a frame moving over a plate of glass, in the center of which the object to be cut is screwed upward through a hole, and may be made to project a distance as small as one thousandth of an inch or thereabout.
Mr. Rutherford exhibited a microscope by the famous Italian maker, Amici, which was presented to him by Amici, when in Italy thirty years ago. The connoisseurs present all agreed that Amici was far ahead of his time, and his instrument, so far as optical effects are concerned, compares favorably with many of the best imported microscopes of the present day.
Professor Julien, of the School of Mines, Columbia College, showed five sections of various stones, such as granite, agate, etc., by means of two Powell & Leland grand binoculars, which have an ingenious arrangement for swinging the polarizer in and out of the tube. Dr. VanderWeyde exhibited four instruments; one by Andrew Ross, to which various attachments had been made to change it into a single dissecting microscope, an inverted chemical microscope, a horizontal microscope especially adapted for drawing, and an instrument to which had been attached an eyepiece for two observers, the invention of the exhibitor. In this device, one observer sees the object under polarized light and the other under unpolarized. Dr. VanderWeyde also showed a large inverted microscope of his own invention, with a colossal eyepiece and a large field (this was illustrated and described in the Record of Scientific Progress for 1865), and also a new polarizing instrument for observing the colored rings around the axes of crystals, whereby the system to which they belong may be determined. The same inventor also showed several little contrivances, which he explained to those interested in practical microscopy, such as new methods of illumination, a new finder, and a micrometer of new and peculiar construction. His most remarkable exhibit consisted of the muscles of the human eye, which contract and dilate the pupil. These muscles can only be revealed by the use of polarized light.
Want of space prevents our mentioning in detail all the exhibits, although many of them deserve honorable mention; but, Zentmayer's improved stand, with rotating and centering stage, an arrangement which causes the mirror to work in the optical axis, McAllister's four microscopes, and those of George Wales and Pike may be specially mentioned. Crouch, of London, was represented by eight splendid instruments, all provided with his own objectives. Wollman exhibited some fine instruments by Queen, of Philadelphia, and four London ones, three by Beck and one by Crouch.
The visitors were all much interested in the exhibition, which will doubtless do much to popularize the fascinating study of microscopy.
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