COMBINATION: VACUUM AND PRESSURE Oil Seal Air-Pump Is a Strictly High Grade Instrument at A VERY LOW PRICE This machine is especially well adapted THREE WAY-S1OPCOCK to High School use as it has a very large capacity, is highly efficient and practically indestructible. Price without gauges, bell-jar plate and three-way-stopcock, F. O. B. River Falls, Wis., only.... Complete as shown in cut.. $45.00 61.00 We shall be glad to send this machine on trial, freight prepaid, to any address in U. S., subject to return at our expense if not perfectly satisfactory in every way. Please write for circular. J. S. HEMENWAY & CO. RIVER FALLS, WIS. Questions For Reviews 45,000 Already Sold Compiled from Recent College Entrance Examinations Separate pamphlets. Price 40 cents each. Liberal discounts on quantity orders. Sample copy half price. Copy for teacher free on adoption for class use. Answers to numerical problems can be supplied to teachers only. Prices on application. Greek, Roman, English; First, and Second Latin; Question Book on History (American, English Write for prices and information University Supply & Book Company 10109 Wilbur Ave., Cleveland, Ohio Please mention School Science and Mathematics when answering Advertisements. MANUFACTURERS AND DEALERS IN CHEMICAL APPARATUS PHYSICAL APPARATUS SPECIAL GLASS APPARATUS School Science and Mathematics Wants Agents in every High School, Normal School, College and University in the country to secure subscriptions for it. Every Science and Mathematics teacher, as well as many professional men and many laymen should be numbered among its subscribers. Write for information. SCHOOL SCIENCE AND MATHEMATICS 2059 East 72nd Place, Chicago, Ill. The Nature Study Review Official Journal American Nature Study Society Brimful of new and down Devoted to all phases of Nature-Study in the school and home. to-date material each month. A frequent comment in our mail: "The Review is one of the best magazines for promotion of Nature-Study and should be in every school." Published monthly except June, July and August. $1.00 per Year. 15c per Copy. (With School Science and Mathematics $3.50 per Year.) Subscribe Now. THE COMSTOCK PUBLISHING CO., Pleuse mention School Science and Mathematics when answering Advertisements. Acceleration This apparatus is exceed- is capable of giving quantitative and consistent results. A roll of special tracing paper, which is fastened to the falling plate is furnished with each piece of apparatus. WM.GAERTNER and CO. Physical Apparatus and Laboratory Supplies 5345-49 Lake Park Ave. CHICAGO, ILL. WAR SAVINGS STAMPS DELIVERED TO YOUR HOME Tear Out-Fill In-Hand Letter-Carrier-or Mail to Post Office TO THE LOCAL POSTMASTER:- Kindly have letter-carrier deliver for which I will pay on delivery: $5. U.S. WAR-SAVINGS STAMPS at $... each 25c. U. S. THRIFT STAMPS at 25c. each. to me on (State number wanted) (State number wanted) Name (Date) (See prices below) Please mention School Science and Mathematics when answering Advertisements. WHATMAN FILTER PAPERS We carry a complete stock of the celebrated Whatman Filters. The chemist will find in this unusual line the grade best suited to his requirements. "PYREX" GLASSWARE ALUNDUM WARE FUSED SILICA WARE KNOTT'S "317" ANTIMONY RUBBER STOPPERS Our New CHEMISTRY-BIOLOGY CATALOGUE (Catalogue 22C) just received from the printers contains complete listings of the above lines, general materials and chemicals. If your name is not on our mailing list, send for this catalogue at once. L. E. KNOTT APPARATUS COMPANY BOSTON (Cambridge "A" Station) MASS. 28 E.Jackson Blvd., Chicago To this organization-national in scope-employers and teachers naturally turn in mak Boston New York Birmingham Denver ing a survey of the whole educational field Portland Berkeley Los Angeles for best teachers and teaching opportunities. Teachers We Need You For the best positions in the West. Write immediately for enrollment card and booklet "How We Place You." The Largest Agency in the West. WM. RUFFER, A. M., Mgr. Rocky Mt. Teachers' AGENCY, Empire Bldg., DENVER, COLO. CAN WE AVOID DISEASE? Sickness is due to the presence of living organisms in your body. If you can prevent the organisms from entering you will not be sick. HAVE YOU EVER SEEN A GERM? We have made photographs thru the microscope of some of the most important disease germs and have made lantern slides from these Photographs. We have also written a Booklet to go with the slides. The booklet summarizes the important facts concerning germs and gives a special paragraph to each germ. There are 15 slides in the set. HELP YOUR COMMUNITY With this set of slides teachers can be of valuable assistance in decreasing the sickness in their own communities. It is not necessary that you take a course in Bacteriology, for the booklet gives you all the facts. The set of slides has been recommended by teachers writing in School Science and Mathematics. [Oct. 1918, p. 607]. The price of the set with the Booklet is $15.00. Write today for further information. THE CHICAGO BIOLOGICAL SUPPLY HOUSE ALL KINDS OF BIOLOGICAL SUPPLIES 5505 KIMBARK AVENUE CHICAGO, ILLINOIS It is more evident every day by the way progressive Science and Mathematics Teachers are keeping up their subscriptions to their professional Journals, especially School Science and Mathematics, that even in these strenuous war times they realize that it is their duty to keep abreast of the times with everything new in their profession in order that they may be doing their share in this great reconstruction period by preparing their pupils for their part in the mighty contest. Subscribe now to School Science and Mathematics. Only $2.50 per year. 2059 East 72nd Place, Chicago, Illinois. Please mention School Science and Mathematics when answering Advertisements. |