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from fatigue belonging to the use of this form of miscroscope; for when placed on a table, rather higher than the one commonly used, and a foot or two from the edge, the observer can recline on his arms, and observe for hours without the slightest sensation of fatigue. Messrs. J. & W. Grunow, New Haven, Conn.,
are the manufacturers of this instrument.
DR. J. LAWRENCE SMITH'S GONIOMETER AND MICROMETER.
Professor Smith has also invented a Goniometer for measuring the angles of crystals under the microscope. It is also combined with a Micrometer. The following is a description of the instrument with the method of using. (Figs. 433-4.)
E is the upper end of the draw-tube of the microscope, with the ring k soldered to it. Over this ring k, screws another ring F, which serves as a support and as a centre to the graduated circle D, which freely, but without shaking, revolves upon the same. Into the bore of the ring F, fits by its lower conical end h, the tube G, which is held in it by a screw-ring y, that prevents its being taken out. Into the tube G, which also has a free revolving movement, fits the positive eye-piece a, d being the field-lens, 8 the eye-lens.
The slide bb, on opposite sides of G, admits of the micrometer with its mounting B, B being introduced into G, and the graduation being brought into the field of the eye-piece.
C is an index, attached to G by the screw c; it may be taken off, when the apparatus is not used as a goniometer.
1 See American Journal of Science and Arts, for September, 1852, in which the entire paper of Prof. Smith will be found.
USE OF THE GONIOMETER.
Bring the object into focus near the centre of the field of the micrometer, apply your finger to the knob K, and revolve the micrometer, till the lines of its graduation are parallel to one
side of the angle to be measured. Revolve then separately the graduated circle, till zero is brought to agree with the point of the index C. Then revolve again the micrometer by the knob K, until the graduation lines are parallel to the other side of the angle to be measured, when the index C will show the value of this angle. (The references are the same in both cuts.) The graduated lines of the micrometer are generally of the American inch apart. But their relative value as micrometer, with the different object-glasses and eye-pieces, must be ascertained by a glass stage-micrometer, and recorded in a table.
Aberration, chromatic, 73, 74.
Acalephs, see Medusa.
Acarida, 581, 582.
Achyla prolifera, 315, 316.
Acineta-form of Vorticella, 419, 420.
Achromatic Condenser, 131-133, 136; use
Achromatic correction, 41; principle of, 73,
Adipose tissue, 607, 608, 664.
Adjustment of Focus, 86, 87; uses of, 162-
of Object-glass, for thickness
Agates, sponge-remains in, 633.
Apple, cuticle of, 389, 390.
Aquatic Box, 148, 169.
ARACHNIDA, microscopic forms of, 581, 582;
Archegonia, of Marchantia, 344-347; of
Arachnoidiscus, 290, 291.
Arcus Senilis, 665.
Air-bubbles, microscopic appearances of, Ascaris, 531, 532.
Alcyonian Zoophytes, 472–474.
Asci of Lichens, 334; of Fungi, 335.
ALGE, higher, microscopic structure of, Asphalte, use of, 207.
Anacharis alsinastrum, rotation in, 364,
Anagallis, petal of, spiral vessels in, 396.
ANNELIDA, 535; marine, circulation in, 535,
Anomia, structure of shell of, 512.
Antherozoids, of Vaucheria, 314; of Sphæ-
Asteriada, skeleton of, 482, 483; metamor-
Avicularia of Polyzoa, 498, 499.
Azure blue butterfly, scales of, 195, 558.
Bacillaria paradoxa, 296; movements of,
Bee, eyes of, 561; proboscis of, 567;
Binocular Microscopes, 114-117.
Bird, Dr. Golding, on preparation of Zoo-
BIRDS, bone of, 587; feathers of, 597, 598;
Blenny, viviparous, scales of, 591.
Blood vessels, injected preparations of,
Bone, structure of, 183, 584-587; mode of
Bowerbankia, 50, 496, 500.
Brachionus, 427, 429, 434.
324; multiplication of, by zoospores, 324;
Chilodon, teeth of, 415; self-division of,
Chirodota, calcareous skeleton of, 486.
Choroid, pigment of, 605.
Chromatic Aberration, 71, 72; means of re
Ciliary action, nature of, 424, 425; on gills
Ciliated epithelium, 606, 607.
Circulation of Blood in Vertebrata, 616-
Brachiopoda, structure of shell of, 513-515. Cirrhipeds, metamorphoses of, 548-530.
Brooke, Mr., his Object-glass holder, 127.
Buccinum, tongue of, 521; egg-capsules
Bull's-Eye Condenser, 143; use of, 178.
Cabinets for microscopic objects, 243.
Cactus, raphides of, 371.
Calycanthus, stem of, 385.
Clarke, Mr. J. L., his mode of preparing
Cleanliness, importance of, to Microscope,
158-160; in mounting objects, 242.
Clypeaster, spines of, 481.
Cockle of wheat, 531, 532.
Camera Lucida, 125, 126; use of, in Mi- Coddington lens 80.
Canada balsam, use of, as cement, 208, 209,
Capillaries, circulation in, 616-619; injec-
Cartilage, structure of, 608, 609.
Chalk, Foraminifera, &c., of, 631-633.
Cohn, Dr., his account of various states of
Coleoptera, mouth of, 565-567.
Collomia, spiral fibres of, 368–370.
Columella of Mosses, 351.
for Opaque Objects. ordinary,
Confervaceæ, 317; self-division of, 318;
Conifera, peculiar woody fibre of, 372; ab.
Conjugation of Palmoglæa, 252; of Des-