Notices respecting New Boohs. 187 



Electricity in Agriculture and Horticulture. By Prof. S. Lemstrom. 

 London : " The Electrician " Printing and Publishing Company, 

 Ltd. 1904. Pp. iv+72. 



The interesting and important experiments which form the 

 subject-matter of this work seem to have definitely established the 

 fact that, under suitable conditions, plant growth is greatly stimu- 

 lated by the feeble electric current which may be made to pass 

 from the soil through the plant to a wire net stretched above it, 

 a deriuite difference of potential being maintained between the net 

 and the earth by means of an electrical influence-machine. A more 

 favourable result is obtained with the current flowing downwards 

 than up wards. According to Prof. Lemstrom, a downward current 

 introduces into the plaut-tissues carbonic acid and nitrogen com- 

 pounds, while an upward one quickens the circulation of the sap. 

 In hot and brio-ht weather, the electrical treatment should be sus- 

 pended, as it has at such times been found damaging to most 

 vegetables. The percentage increase in the crop due to the 

 electrical treatment is at least 45 per cent, for land of average 

 fertility. In view of these results, which seem fairly well established 

 by numerous experiments, the use of an electrical stimulus certainly 

 comes within the range of an economic possibility, especially as the 

 plant required for the purpose is very simple and cheap, and the 

 power necessary to keep it running is absurdly small. To those 

 practically interested in agriculture or horticulture, we strongly 

 recommend the careful study of Prof. Lemstrom's book, where they 

 will also find full details regarding the cost of the necessary plant 

 and directions for using it. 



Dr. J. Fricls Pliiisilcalische Technik. Von Dr. Otto Lehmann. 

 Erster Band. Erste Abteilung : Braunschweig: F. Vieweg und 

 Sohn. 1904. Pp. xxiv-r-630. 



It is some fifty years since there appeared in Germany a book 

 on physical workshop practice by Dr. J. Prick, the main object of 

 which was to counteract the pernicious effects of the chalk-and- 

 blackboard style of teaching Physics so prevalent in his day in 

 Germany as elsewhere. The book achieved an immediate and re- 

 markable success, and ran through several editions during the 

 author's lifetime. !Xo higher tribute could be paid to its enduring 

 educational value than the fact that an enlarged modern edition of 

 it now appears, the laborious task of editing and bringing it up 

 to date having been undertaken by Prof. Lehmann. 



The present volume, which is Part I. of Volume I. of the complete 

 work, is divided into five chapters, and may be said to deal with 

 preliminaries. In the first two chapters we have a very 

 complete discussion of the architectural features of a Physical 

 •• Institute.*' and the design of the lecture-theatre. The various 

 fitting> connected with this latter, including blackboards, water, 

 team, electric circuits and switchboards, projection apparal us, 

 heating and ventilation, &c. are dealt with in considerable detail, 



