pieces being the softest possible cast iron. The magnets and the pole-pieces form a solid frame, being held together by nuts on the tapped ends of the magnets. The armature, which is of the Gramme type, is supported by brackets of brass bolted to the polepieces, and the shaft runs in phosphor-bronze bearings fitted to the brackets. The armature is made of annealed wrought-iron wire supported by a three-armed spider of brass. The brush arrangement is of improved construction, original with the designer, and enables the tension of the brushes to be adjusted without disturbing the setting of the same, and without exposing the attendant to shocks from the machine. This is effected by an insulated thumb-screw, - aside from the thumb-screw that holds the brushes, which clamps the brush-holders to the brushpin. The rocker-arm is also movable. The cables from the brushes are carried to a board on top of the machine, on which are two horse-power, and, being very compact, occupies a floor-space of only ten by nineteen inches, with a height of twelve inches. The armature is of the Gramme ring type, and the pulley end of the shaft has its bearing in the neutral part of the field-magnet. The shaft is of English tool steel of the best quality, the bearings are ground true on dead centres, and the armature is so attached as to practically constitute a portion of it, avoiding all danger of loosening, - a point of importance in this class of machinery. Ball bearings are used, admitting of self-alignment. They are made of phosphor-bronze, hand-reamed, and of considerable length, to give an even bearing surface and prevent all tendency to heat. The commutator sections are of drop-forged copper, hard, and of almost pure metal. The commutator is attached to the armature in a novel manner, and can be renewed without disturbing the armature wires. placed the terminals; also a switch for short-circuiting the field-coils, in case it is desired to "paralyze" the machine while running. Thus the switch and terminals are always in sight, and can be attended to at once, if necessary. A remarkable feature of this dynamo is that it requires exceedingly small floor-space for its capacity, - a feature of great value when the space is limited, as on board of ships, etc. The floorspace required for a twelve-light dynamo is only twenty-four by twenty-four inches. A New Constant-Current Electric Motor. THE electric motor shown in the accompanying illustration is one of a series manufactured and placed on the market by the Electric Engine Company of Cincinnati. It is intended to run on a constant-current or arc-light circuit, has a maximum capacity of The armature is accurately adjusted to a running balance, and provided with means for forced ventilation. The ordinary rockerarm supporting the brush-holder has been dispensed with, thus rendering the important parts more readily accessible. The governor, the construction of which is shown in the figure, maintains the speed constant under all variations of load from zero to the full designed load of the machine, and is remarkably simple, having but one wearing point. It regulates solely by variation of pressure, practically eliminating motion and wear: hence it has great durability and sensitiveness. For constant potential circuits, this company manufactures motors of similar design, but differing in detail. As they regulate automatically, they do not require governors. These are made for standard potentials of 110, 220, and 550 volts, though they may be made for any specified voltage. Exchanges. [Free of charge to all, if of satisfactory character. Address N. D. C. Hodges, 47 Lafayette Place, New York.] 66 Will exchange "Princeton Review" for 1883, Hugh Miller's works on geology and other scientific works, for back numbers of The Auk," " American Naturalist," or other scientific periodicals or books. Write.-J. M. Keck, Chardon, Ohio. A collection of fifty unclassified shells for the best offer in bird skins; also skins of California birds for those of birds of other localities. Address Th. E. Slevin, 2413 Sacramento St., San Francisco; Cal. I have forty varieties of birds' eggs, side blown, first class, in sets, with full data, which I will exchange for books, scientific journals, shells, and curios. Write me, stating what you have to offer. - Dr. W. S. STRODE, Bernadotte, Fulton County, Ill. "I wish to exchange Lepidoptera with parties in the eastern and southern states. I will send western species for those found in other localities. "-P. C. Truman, Volga, Brookings Co., Dakota. Shells and curiosities for marine shells, curiosities or minerals address W. F. Lerch, No. 308 East Fourth St., Davenport, Iowa. I want to correspond and exchange with a collector of beetles in Texas or Florida. Wm. D. Richardson, P.O. Box 223, Fredericksburg, Virginia. 100 botanical specimens and analyses for exchange. Send list of those desired and those which can be furnished, and receive a similar list in return. Also cabinet specimens and curiosities for the same. Scientific correspondence solicited.-E. E. BOGUE, Orwell, Ashta. County, O. I will sell to chapters or individual members of the Agassiz Association, 25 fine specimens of fossil plants from the Dakota group (cretaceous), correctly named, for $2.50. Send post-office order to Charles H. Sternberg (author Young Fossil-Hunters"), 1033 Kentucky Street, Lawrence, Kan. One mounted single achromatic photographic lens for making 4X5 pictures, in excellent condition; also one "new model double dry-plate holder (4" X 5"), for fine geological or mineralogical specimens, properly classihed. Charles E. Frick, 1019 West Lehigh Avenue, Philadelphia, Penn. The undersigned wishes to make arrangements for the exchange of Lepidoptera of eastern Pennsylvania for those from other localities. All my specimens are named and in good condition. - Charles S. Westcott, 613 North 17th Street, Philadelphia, Penn. California onyx. for minerals and coins not in my collection.-W. C. Thompson, 612 East 141st Street, New York, N.Y. cents. CHAMBERS, G. F. A Handbook of Descriptive and HOUSTON. E. J. A Dictionary of Electrical Words, KAPP, G. Alternate-Current Machinery. (Van Nostrand KLEMM, L. R. European Schools; or, What I saw in gestibility, and Nutritive Value of Food. New York, MURDOCK, H. The Reconstruction of Europe. Boston NICHOLS, W. F. Topics in Geography. Boston, Heath. PARKES, L. C. Hygiene and Public Health. Philadel- REDWAY, J. W. The Teacher's Manual of Geography. SARGENT, C. S. Scientific Papers of Asa Gray. Vol I. GUARANTY INVESTMENT COMPANY CAPITAL $250,000. 7% Guaranteed Farm Mortgages 7% The Company sends each year to Kansas and Nebraska for the purpose of examining its loans and methods of business a COMMITTEE OF INVESTORS. The Committee for 1889 visited Fifty counties in the two States, examined over 100 farms on which loans had been made and reported every one to be SAFE. The Company will be glad to send to any address the Report of the Committee which presents a very interesting statement of the general development of Kansas and Nebraska. A large number of loans equally as good as any examined by the Committee are always on hand for sale. Address for Monthly Bulletin and Investors' Committee Report HENRY A. RILEY, General Eastern Manager, 191 Broadway, N. Y. Executive Office, 115 Broadway, N. Y. FACTORY, JERSEY CITY, N. J. Please Mention "Science." Oct. 9. President Meier presented a discussion of a new tractor recently invented by H. L. Van Zile, an engineer of Albany, New York. The invention had resulted from certain mathematical investigations, and rendered it possible to make the total power, or pulling force, available for traction. A model had been made, which easily mounted a 20-per-cent grade, while the same model without the improvement could as American Journal of Philology. Building (weekly).. cend only a 10-per-cent grade. In the dis- 95 MILK ST., BOSTON, MASS. Cosmopolitan, The cussion, Robert Moore called attention to the similarity of this device to the Fell tractor, which was in successful use on the Summit This Company owns the Letters Patent granted to Alexander Graham Bell, March 7th, 1876, No. 174,465, and January 30, 1877, No. 186,787. Railway, over Mount Cenis. Professor Gale remote from civilization. Considerable in- teresting engineering data were presented, American Institute of Electrical EST Electrician and Electrical Engineer. Forum, The.. Harper's Bazar. Journal of Philology (Eng.) Macmillan's Magazine.. Magazine of American History. North American Review. STEEL PENS. Outing OF SUPERIOR AND STANDARD QUALITY. For Sale by all Stationers. THE ESTERBROOK STEEL PEN CO., Readers of Science Oct. 15. A paper was read by Mr. Thomas D. Lockwood, member, entitled "Electrical Notes of a Transatlantic Trip." It embraced some observations on telegraphy; description of the London operating ing the paper. Corresponding with or visiting Advertisers will confer a great favor by mention Overland Monthly. Portfolio, The.. Practitioner.. Puck (German).. Quarterly Review (London).. St. Nicholas.. Scientific American... Supplement.... ...... Architect and Builders' edition.. Texas Siftings.. Trained Nurse.. Year's Subscription. With Science. Wants. Any person seeking a position for which he is qualified by his scientific attainment, or any person seeking some one to fill a position of th. character, be it that of a teacher of science, chemist, draughtsman, or what not, may have the Want' inserted under this head FREE OF COST, if he satisfies the publisher of the suitable character of his application. Any person seeking information on any scientific question, the address of any scientific man, or who can in any way use this column for a purpose consonant with the nature of the paper, is cordially invited to do so. ANTED. By a large manufacturing man about twenty years of age, to make working drawings of electrical instruments from free-hand sketches and verbal assistance. Must be able to execute tinted drawings and tracings as well, and have a fair knowledge of general physics and principles of electrical measuring instruments. One who has had some practice in brass and machine work preferred, as also one who will remain and learn the business. Specimens of work required. Address, stating salary expected, experience and references, E. G. W., SCIENCE Office, N.Y. City. Old and Rare Books. Catalogue No. 29 nearly ready. Will contain many scarce works pertaining to Natural History, Americana, out of print books, as a whole, interesting. ANTED a young man with some knowl- for Science is now ready, and will be mailed Wedge of mineralogy to assist in our Min eral Department. A. E. FOOTE, 1223 Belmont Av., Philada., Pa. postpaid on receipt of price. ECHANICIAN. An optician and maker NEW HANDY of instruments of precision of experience would be glad of a position where his skill would be valued in connection with some higher educational institution. Address G. J., care of SCIENCE, 47 Lafayette Place, New York. Half Morocco - 75 cents. This binder is strong, durable and elegant, has gilt side-title, and allows OFFICE and MANUFACTORY: 402 and 404 Greenwich Street, New York City. New England Office, 19 Pearl St., Boston Philadelphia Office, 301 Arch St. Western Office, 139-141 Adams Street Chicago. Southern Office, 25 Carondelet Street, New Orleans. Agassiz Association. Does your Chapter want a good collection or library? Sometimes there are not enough funds in sight to make the purchase. If so, satisfactory arorder and balance in small monthly payments. rangements can be made by paying part with tract to fill it out to any desired extent and Where a collection already exists we will conkeep the cost within the resources of the chapter. we will send boxes of samples upon approval. To parties who cannot see our specimens here We issue no catalogues. A. A. mineral collection. 64 large beautiful specimens, ready mounted, in handsome walnut cabinet. Each specimen represents one of the 64 sub-divisions in Dana's Tables for the Determination of Minerals. With each collection we send copy of Dana's Manual and complete set of determination apparatus with blow-pipe, acids, etc., etc. Everything first class. Price complete, $40.00 $20 down, and balance $5 per month. Cheaper collection can be supplied if wanted. A. A. chapters, scientific societies and clubs, colleges, schools, and private individuals, desiring rare specimens, or books, or collection of the same, please write to 4% In. Long. W. H. WINKLEY, Clearfield, Iowa. PATENT WRENCH AND SCREW DRIVER COMBINED. Turns Nuts, Gas Burners or Pipe without adjustment. Made of Best Polished Steel. Sent by mail for 25 cts. CHARLES U. ELY, P. O. Box 1945, New York City. ESTABLISHED 1859. H. A. DREW, Commercial Printer, the opening of the pages perfectly 37 Clinton Place, near Broadway, flat. Any number can be taken out or replaced without disturbing the others, and the papers are not muti lated for subsequent permanent bind New York. or Wedding Orders, Souvenirs, Invitations, Oring. Filed in this binder, Science is ders of Dance, etc., etc., done in the latest and always convenient for reference. SILKS. JAMES MCCREERY & CO. are showing for Bridal Dresses, Evening, Dinner, Reception, and Street Costumes, in Metal, Silks and Velvets, the Richest and most Beautiful Designs and Combinations procurable. In low and medium-priced Novelties, ladies will experience no difficulty in finding goods suited to the various uses to which Fancy Silks can be applied. Dress Silks in the latest Colorings and the newest and most approved Weaves, from 85 cents to $4.00 a yard Mail Orders receive most careful attention. Arnold, Constable & Co ACES AND GAZES-Point and Duchesse Collars Duchesse Point and Applique, with trimming laces L and sets in Van Dyke effects. Bridal Veils in to match. Real lace Handkerchiefs, Duchesse and Valenciennes, Mousseline de Soles Embroideries, flounces and all overs in choice evening shades. Black Lace Drapery Nets, White and Colored, Plain and Fancy Crepes and Crepe de Chine for evening toilets. PARIS DRESSES AND CLOAKS.-Costumes for Evening, Dinner, Reception and Promenade, Tea Gowns, Matinees, Suits, Wraps, Sacques, Cloaks, Long Garments, Opera Wraps and Jackets. Also, those of our own manufacture, from Paris styles, in the most fashionable fabrics. URS AND FUR TRIMMINGS.-Sealskin Sacques, Dolmans, Jackets and Paletots (London dye), Blue Lynx, Alaska Sable and Krimmer. Shoulder Capes, Pelerines and Muffe. Fur Trimmings. MORRIS EARLE & CO. SUCCESSORS 10 R. & J. BECK, 1016 Chestnut Street, Phila. Microscopes and all Accessories and Apparatus. Photographic and Photo-Micrographic Apparatus and Outfits. Spectacles, Eye Glasses, Opera and Marine Glasses, etc. Illustrated Price List mailed free to any address. Mention SCIENCE in corresponding with us. J. GRUNOW, 621 Sixth Avenue, New York. Established 1852. MAKER OF Microscope Stands, Broadway & 19th st. Oil Immersion Object NEW YORK. ives and Abbe Condensers for Bacterial and Histological work, USEHOLD MICROSCOPE of Objectives, Camera E. & H. T. ANTHONY & CO. 591 Broadway, N.Y. Manufacturers and Importers of PHOTOGRAPHIC INSTRUMENTS, Apparatus and Supplies of every description. Sole proprietors of the Patent Detective, Fairy Novel, and Bicycle Cameras, and the Celebrated Stanley Dry Plates. Amateur Outfits in great variety, from $9.00 upward. Send for Catalogue or call and examine. More than 40 years established in this line of business. FOOD And its Detection. With photomicrographic plates and a bibliographical appendix. By J. P. Battershall. 328 pages, 8vo, cloth. Price, $3.50. Circulars and Catalogues on application. E. & F. N. SPON, 12 Cortlandt St., New York. Readers of Science Corresponding with or visiting Advertisers will confer a great favor by mentioning the paper. to any address for $5.00 This instrument is simply for use by a beginner in Microscopy. The finer Microscopes vary in value from $25. to $250. Send for catalogue to G. S. WOOLMAN, SOMETHING NEW STRONGEST Lucida and other accessory apparatus. IMPROVED OIL LIGHT MAGIC LANTERNS. Also Lime and Electric Light Apparatus, and mechanical, plain, and fine colored views. J. B. COLT & CO., Manufacturers, No. 16 BEEKMAN STREET, NEW YORK. MINERALS. International Mineral Cabinets, specimens from Europe, Asia, Africa, S. America, Mexico, Greenland, Canada, and U.S. 100 spec., $3.50; 50 spec., $1.75; 25 spec., $1, each collection in handsome polished hard-wood case, expressage prepaid, Finest stock of specimens in U.S. Minerals for blowpipe analysis by the pound cheap. Complete Catalogue Free. Consignments from all parts of the world constantly arriving, GEO. L. ENGLISH & CO., Dealers in Minerals, 1512 Chestnut St., Philadelphia, Pa. |
