iv. PREFACE. 
varying value in different countries ; but as these quantities 
form in the total cost only a small part, this does not affect 
the calculations in a serious way. 
THE AUTHOR. 
PUBLISHER’S NOTE. 
The Publisher is desirous of placing Prof. Lemstrém’s 
interesting work before the public, with the view of hasten- 
ing the time when the utilisation of the electric current in 
agricultural and horticultural work will become a recognised 
development of the science and industry of up-to date 
cultivation of the land for market crops. That this deve- 
lopment will be advanced by Prof. Lemstrém’s valuable 
experiments there can,.the Publisher considers, be no 
question. 
As the greater part of the Author's scientific determina- 
tions regarding temperatures are made in Centigrade 
degrees, and for other measurements in the metric system, 
the Publisher, in accord with the Author’s wishes; and de- 
sirous of facilitating the reading of this book, has printed 
on the last pages tables containing a Figure showing the 
relations between the different thermometers, and a Table 
showing the metric measures (with their signs) in English 
measures. The Table is attached in such a manner that it 
can be readily consulted by the reader during his reading 
of the book. 
