CONTENTS OF THIS NUMBER. Illustrated Articles are marked *. The Germ Theory of Disease, and its Present .... JOHN BYRNE, Astronomical and Terrestrial Telescope Maker, 314 East Twenty-first Street, New York. Telescopes of all sizes made to order; also, Telescopes corrected and carefully repaired at short notice. All work warranted correct. Testimonials from Lewis M. Rutherfurd, Esq., show the value of my object-glasses. OF BEST THIN GLASS CIR 250 TWO OUNCES CLES and SQUARES, in 252 equal proportions, sent post free on receipt of two dollars. One dozen and a half of unmounted objects for one dollar, post free. Address CHAS. PETIT, 253 The Woodward Prism...... .... *The Weber Slide.................................. 151 High Street, Stoke Newington, London, England. A New Form of Stage Forceps. A Correction and an Apology. A Correction..................................... Our Book Table......... Correspondence. On Objectives...... A Query for Mr. Merriman... .............. ........ San Francisco Microscopical Society...... State Microscopical Society of Illinois............ 263 Mr. Geo. Wale has devised a new and very simple form of stage forceps, which is shown in the accompanying cut. These forceps are very neatly made, and the price is only $1.25, for which sum they will be sent by mail post paid. INDUSTRIAL PUBLICATION COMPANY, Microscopical Section, Troy Scientific Association 264 SECOND-HAND BOOKS, Exchanges.. CLASSIFIED CATALOGUE OF 264 MICROSCOPE WANTED. In exchange for a Fine GOLD WATCH, English Micro-Photographs. A series of 80 Micro-Photographs-3% ty 3 inchesfrom nature, by Dr. Maddox, of England, illustrating the whole field of Microscopy. For lecture or educational purposes it is most valuable, it being the only connective series ever made; the original plates are partly destroyed. Podura Scale and Angulatum shown on screen 6 feet in diameter, with perfect definition and Cata- "THE LENS.” correct markings. To be sold for moderate price. Ad TAXIDERMIST, dress LANTERN, Care of this Journal. MICROSCOPE WANTED, I wish to procure a Microscope, and would like to hear from any one having a good second-hand instrument Address which he is willing to sell cheap for cash. J. ROGERS, Care of this Journal. NO. 32 NASSAU STREET, BROOKLYN, N. Y., Keeps constantly on hand for sale, Sheet Cork for insect boxes-size, 12 x 81⁄2 x 1⁄2-$1.25 per dozen sheets. Entomological pins, of Klager and other German makers, Also, dealer in Native and Exotic Bird $1.25 per 1,000 Skins, Birds' Egga, Insects, etc., etc. N. B. The above prices do not include the cost of transportation. USEFUL BOOKS. MICROMETERS. With Plain Directions for Acquiring THE ART OF SHOOTING ON THE WING. Useful Hints concerning all that relates to Guns and Shooting, and particularly in regard to the Art of Loading so as to Kill. To which has been added several valuable and hitherto secret Recipes, of great practical importance to the Sportsman. By an Old Gamekeeper. 12mo., cloth. Illustrated. 75 cents. The Pistol as a Weapon of Defence, in the House and on the Road; How to Choose it and How to Use it. 12mo., Cloth. 50 cents. The Chemical History of the Six DAYS OF CREATION. By JOHN PHIN. 12mo., 75 cents. Lightning-Rods and How to Con cloth. STRUCT THEM. By JOHN PHIN, Editor of The Technologist. 12mo.. Cloth. 50 cents. What to Do and How to Do It IN CASE OF ACCIDENT-In the Household, the Workshop, the Factory, and the Mine, and on the Farm, the Railroad, and Everywhere. Cuts, Burns, Bruises, Sprains, Poisons, Drowning, etc., etc. The best book on the subject. 12mo., cloth. 50 cents. How to Use the Microscope. Second Edition, greatly enlarged and fully illustrated. Four full page engravings. 12mo., Cloth. 75 cents. The Construction, Adjustment, TESTING AND USE OF OPTICAL INSTRUMENTS (Microscopes, Telescopes, etc.) By J. F. Heather, A. M.. 75 cents. Common Objects for the MicroSCOPE. By the Rev. J. G. Wood. Upwards of four hundred illustrations including twelve colored plates by Tuffen West. 50 cents. 1000 Objects for the Microscope. With 13 plates and over 500 50 cents. By M. C. Cooke. figures. The Microscopist's Companion. By JOHN KING, M. D. This book was published in 1859, and contains engravings of the microscopes made by the principal American makers of that time (Spencer, Grunow and others.) These engravings and descriptions are historical, and can be found nowhere else. In addition to this, it contains much interesting matter, and a very complete Dictionary of microscopical terms. The work is now scarce, but we have secured a few copies, which we offer, post paid. for $2 each. The Microscope. By ANDREW Ross. This is a reprint of the famous article contributed by Ross to the "Penny Cyclopædia," and so often referred to by Carpenter, Brooke, Hogg and others. It should be carefully studied by those who desire to understand the construction of the microscope. 12mo., Cloth. Fully illustrated. 75 cents. Practical Directions for CollectING, PRESERVING, TRANSPORTING, PREPARING AND MOUNTING DIATOMS. BY PROF. A. MEAD EDWARDS, M. D.; PROF. CHRISTOPHER JOHN STON, M. D.; PROF. HAMILTON L. SMITH, LL. D. This volume undoubtedly contains the most complete series of directions for collecting, preparing and mounting diatoms ever published. 12mo. Cloth. 75 cents. The following Micrometers have been made on a new machine just constructed at great expense. Careful examínation shows that they are as accurate as any in market. The Micrometer is an indispensable accessory to every microscope, for by it we are enabled to tell not only the size of the objects which we are examining, but the magnifying power of our microscopes. For the latter parpose we must use a micrometer whose divisions are less than the field of view of the microscope we are using, and the greater the magnifying power, the less is the absolute size of the field of view. corresponding to different magnifying powers: In the following table we give the field of view 25 diameters shows .25 inch. 1000 (6 .0125" .005 " micrometer divided into 100ths answers very well. With For microscopes magnifying less than 100 diamters a microscopes magnifying more than 100 times, the micrometer should be divided into 1000ths; and when a magnifying power of over 500 times is used, a division of 5000 to the inch is not too fine. micrometer is fully understood, every owner of a microFeeling assured that when the practical value of the scope will procure one, we have placed the price of these micrometers at less than half that usually charged. The cost of making micrometers depends very much upon the number made. To make a hundred costs very little more than to make ten. Micrometers, ruled on glass slips, 3 by 1 inches100 to the inch......... 100 and 500..... ..... 100 and 1000................................... 100, 1000 and 2000............................................................... 100, 1000 and 5000..... ................ Micrometers ruled on Ivory- $ 75 85 1.00 1.25 1.50 These are made specially for the use of Botanists, Entomologists. Mineralogists, etc., and are intended to be used with dissecting microscopes or simple microscopes100 to the inch..20, 30 and 50 cents, according to quality. 200 to the inch.. 80 cents. INDUSTRIAL PUBLICATION COMPANY, 176 BROADWAY, NEW YORK. Vol. I-No. 9.-Diatoms as Food for Plants..10 cents. Vol. III-No. 8.-On the Life History of a Minute Septic Organism, with an Account of the Experiments made to Determine its Thermal Death Point. By Rev. W. H. Dallinger. With two fine plates. This is probably the most important contribution to this subject that has been made in recent years............25 cents. Vol. III-No. 10.-Volvox Globator. A very complete paper on this interesting microscopic object. With fine plate..... .....25 cents. Address AMERICAN JOURNAL OF MICROSCOPY. Box 4876, New York. BINOCULAR MICROSCOPE STAND "A" (ONE-THIRD ACTUAL SIZE). MECHANICAL CONCENTRIC ROTATING AND ADJUSTABLE STAGE, CENTERING AND ROTATING SUB-STAGE, AND IRIS DIAPHRAGM. Binocular, Five Eye-pieces and Iris Diaphragm..... $225.00 175.00 CLINICAL THERMOMETERS WITH INEFFACABLE INDEX. MICROSCOPES FROM $5.00 TO $1,350.00. 921 Chestnut Street, Philadelphia. W. H. WALMSLEY, Manager Thin Sections of Rocks, AND OF ALL HARD MATERIALS, FOR THE MICROSCOPE, MADE TO ORDER. Mounted Thin Sections of Teeth, Silicified Wood and Corals, and of over 300 Rocks and Minerals, American and Foreign, kept in stock. Specimens sliced and polished to order. Lathes and all supplies for grinding and mounting thin sections. STANDARD COLLECTIONS. POPULAR COLLECTION. 30 Choice Thin Sections for Polariscope, etc., selected from stock. LITHOLOGICAL COLLECTION, II. TYPICAL AMERICAN ROCKS. 30 Thin Sections, with box, and Commentary giving description of each slide. LITHOLOGICAL COLLECTION, III. (Just Ready). TYPICAL ROCKS OF NEW HAMPSHIRE. 30 Thin Sections, with box, and Commentary by G. W. Hawes, of the Geological Survey. Prices of these Collections, on short slides, 45 by 25 mm., $14; on 3 by 1 inch slides, $15. With smaller sections, $8. Price of 30 hand specimens of rocks, corresponding to II or III, $7.50. Send for Catalogue to ALEXIS A. JULIEN, School of Mines, Columbia College, 50th Street, cor. 4th Avenue, New York City. JAMES W. QUEEN & CO., OPTICIANS, 924 Chestnut Street, Philadelphia, MANUFACTURERS OF MICROSCOPES, And Other Optical Instruments. SECOND-HAND MICROSCOPES. BECK'S, CROUCH'S, ROSS', NACHET'S HARTNACK'S, ZENTMAYER'S AND OTHER MAKERS, FROM 25 TO 50 PER CENT. BELOW SEND THE CATALOGUE PRICES. LIST. NOTICE. We have just received from Carl Zeiss, of Jena, a sample lot of his celebrated Objectives, which are for sale at moderate prices. From Ross & Co., a few of Wenham's Reflex Illuminators, price $17.50. From Edmund Wheeler, some fine Podura Scales, P. angulatum, N. rhomboides, A. pellucida, and other tests, besides many other objects, Animal, Vegetable and Mineral. MISFIT CARPETS. (Trade Mark Copyrighted.) English Brussels, Three-Ply and Ingrain. Elegant Stair Rods; also Stair Carpets, Carpet Lining, Velvet Rugs, Oil Cloths, Crumb Cloths, Mattings, &c., &c., very cheap, at the old place, 112 FULTON STREET, NEW YORK. Carpets carefully packed and sent to any part of the United States, C. O. D., free of Express Charges. Call or send for Explanatory Circular and Price List. J. A. BENDALL SOMETHING NEW. I have completed arrangements whereby I am enabled to furnish MICROSCOPIST'S RULINGS on glass, absolutely accurate, and at very low prices. I would especially recommend the 12-band rulings. The bands vary in lines by 10000 to the inch, and are very similar to the noted Nobert's lines, while their low price puts them within the reach of all interested in the microscope. G. S. WOOLMAN, Optician, 116 Fulton Street, New York. MICROSCOPES AND ACCESSORIES OF ALL MAKERS. |