A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE 



' ' To the solid ground 

 0/ Nature trusts the mind which builds for aye." — WORDSWORTH 



MACMILLAN & CO., Publishers, 22 Bond St., NEW YORK. 



VOL. 21 



No. 7 



THURSDAY, DECEMBER 18, 1879. 



Price 15 Cents * 

 Annual Subscription;^ 







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Our Priced and Illustrated Catalogue will be published in four parts, any or all of which will be mailed on application. 



Part ist-Mathematical Instruments, 160 pages ; contains list and prices of Drawing Implements, Drawing Materials, 

 Pocket Compasses, Surveying Compasses, Engineers' Transits and Levels, Surveying Chains, Tape Meas- 

 ures, Pocket Rules, and Books relating to Drawing, Engineering, and Mechanics. 



Part 2d-Optical Instruments, 144 pages ; contains list and prices of Spectacles, Eye-glasses, Lenses, Spyglasses, 

 Telescopes, Opera and Field Glasses, Graphoscopes, Stereoscopes, Camera-Obscuras, Camera-Lucidas, 

 Microscopes, Microscopic Preparations, and Books on Optics and Microscopy. 



Part 3 d-Magic Lanterns and Slides, 112 pages ; contains list and prices of Magic Lanterns for Toys, for Public and 

 Private Exhibitions, Sciopticons, Stereopticons, Scientific Lanterns, and accessory apparatus to be used 

 with them ; Magic Lantern Slides, both colored and uncolored. 



Part 4 th-Physical Instruments, 188 pages; contains list and prices of Instruments to illustrate Lectures in every 

 department of Physics and Chemical Science, Air Pumps. Eleetric Machines, Galvanic Batteries, Barome- 

 ters, Thermometers. Rain Gauges, Globes, Spectroscopes, Auzoux's Anatomical Models, and Books relat- 

 ing to Scientific Subjects. 



JAMES W. QUEEN & CO., 



Mathematical, Optical, and Philosophical Instrument Makers, 

 924 Chestnut Street, Philadelphia. 



