SCIENCE-ADVERTISEMENTS 



JUST ^PUBLISHED 



Mayne and Hatches 

 High School Agriculture 



By D. D. MiYNE, Principal of Sctiool of Agriculture and 

 Professor of Agricultural Pedagogics, TJuiTersity of Min- 

 nesota, and K. L. Hatch. Professor of Agricultural Edu- 

 cation, University of Wisconsin. 



$1.00 



This course has a double yalue for pupils in the first years 

 of the high school. On the one hand, it puts the study of 

 agriculture on a serious basis, and teaches the young be- 

 ginner how he can carry on the work of a farm most pro- 

 fitably. On the other hand, it affords an interesting intro- 

 duction to all the natural sciences, enabling the student to 

 master certain definite principles of chemistry, botany, and 

 zoology, and to understand their application. A few ex- 

 periments are included, which may be performed by the 

 student or by the teacher before the class. But the subject 

 is not made ultrascientific, forcing the student through the 

 long process of laboratory method to rediscover what scien- 

 tists have fully established. The topics are taken up in the 

 text in their logical order. The treatment besins with an 

 elementary agricultural chemistry, in which are discussed 

 the elements that are of chief importance in plant and ani- 

 mal life. Following in turn are sections on soils and ferti- 

 lizers ; agricultural botany ; economic plants, including 

 field and forage crops, fruits and vegetables; plant diseases; 

 insect enemies ; animal husbandry; and farm management. 



American Book Company 



New York Cincinnati Chicago 



JVST PUIil^ISHBD 



The Mathematical 

 Theory of Heat Conduction 



With Engineering and Geological Applications. 



By L. R. IngersoU, Assodale Professor of Phyiia, and O. J. 

 Zobel, Formerly Fellow in Physcs, Universily of Wisconsin 



8vo, cloth, 171 pages, with diagrams. $1.60 



This book may be used as a first book in Mathe- 

 matical Physics, and it will also be serviceable to 

 geologists and engineers. The applications take up 

 and solve practical problems, many of which are 

 here treated for the first time.. 



Questions of the cooling of the earth with and 

 without radioactive influences, and several cases of 

 cooling magmas, are among the problems included 

 for the geologist ; while in technical lines, problems 

 in the tempering of steels, freezing of concrete, 

 electric welding and other examples are considered. 



The applications are numerical in nature, based 

 on the best obtainable data, and illustrated with 

 numerous diagrams. Their reading is facilitated by 

 numerous mathematical and physical tables in an 

 appendix, which serves in great measure to make 

 the book complete in itself. 



GINN & COMPANY 



Boston New York Chicago London 



Atlanta Dallas Columbus 



San Francisco 



INSTRUMENTS OF PRECISION 



For the Study of the Circulation 



JAQUET SPHYGMOCARDIOGRAPH for the simultaneous recording of three different tracings in additio to 

 the chronograph record. One tambour must always record the pulsation of the radial artery with which it 

 is in contact when the instrument is in position. The other two tracings may be from the carotid, jugular, 

 apes beat, etc., as desired. 



USKOFF SPHYGM070N0GRAPH. The unique feature of this instrument is the simultaneous recording of the 

 blood pressure in millimeters of mercury together with the brachial pulse at varying pressures, and one other 

 tracing such as the carotid or jugular pulse or apex beat, and also time in J th seconds. In other words, there 

 are four tracings upon the paper, three of which are fixed by the limits of the apparatus, i. e., blood pressure 

 in millimeters of mercury, arterial pulsations at various pressures and time tracing, while the fourth record 

 may be taken at pleasure from either the jugular vein, carotid artery or apex beat. 



MACKENZIE INK POLYGRAPH. Original English make. This instrument records two simultaneous tracings 

 only. i. e., radial pulse and other, such as carotid, jugular, apex beat, etc., the great advantage being the 

 avoidance of smoked paper and the convenience and permanency of the ink tracings, which maybe continued 

 almost to any length from the long roll of paper supplied with the instrument. 



ELECTRO-CARDIOGRAPH APPARATUS. In this outfit the electro-motive force from the contracting heart 

 muscle is measured by the use of the Einthoven String Galvanometer, an instrument of exceeding sensibility. 

 A fine platinum or quartz thread constitutes the suspension of the galvanometer, the thread being deflected 

 to one Bide or the other as the electro-motive force from the heart varies in strength. By the use of an arc 

 lamp and a microscope system, the thread being of microscopic fineness, a photograph of this thread is 

 thrown upon a sensitized paper which is set in motion during the exposure. 



Send for 



- new illustrated pamphlet "Instruments of Precision for the Study of the Circulatio 

 after Jaquet, Uskoff, Mackenzie and Einthoven*' 



ARTHUR H. THOMAS COMPANY 



Importers and dealers 



WIICROSCOPES, LABORATORY APPARATUS AND CHEMICALS 



WEST WASHINGTON SQUARE, PHILADELPHIA 



(230-2-4 SOUTH SEVENTH ST.) 



