758 



SCIENCE 



[N. S. Vol. XXXVII. No. 959 



An interest in plants is a natural one. Plants 

 are everywhere about us, and are useful in 

 many and exceedingly important ways. The 

 botanical teaching of the last ten or fifteen 

 years has been missing its opportunity to 

 serve and take advantage of this interest, by 

 busying itself too exclusively with plants 

 which most people never see except in the 

 class room, and in which they have no prac- 

 tical interest. 



The old course of study made better use in 

 many respects of one term than the newer 

 course has done of a year. It left much to 

 be desired and the newer course made up its 

 shortcomings; but it did this at too great an 

 expense when it threw away the familiarity 

 with the different kinds of common flowering 

 plants, and the excursions, and the love of the 

 woods which the students gained in old-time 

 classes. There are hopeful signs of a back- 

 ward swing of the pendulum. And it is well 

 that this come before field botany is quite 

 forgotten. 



E. B. COPELAND 

 INDOOR HUMIDITT 



To THE Editor of Science: Notwithstand- 

 ing the conclusions reached in Dr. Ingersoll's 

 interesting letter on this topic, something 

 may perhaps be said in favor of a humidity 

 considerably higher than 40 per cent., and 

 nearer the 66 or YO per cent, favored by " most 

 authorities." 



The writer has made experiments similar to 

 those of Dr. Ingersoll, but with the following 

 differences: gallons evaporated per day, 18 to 

 20, instead of 25 or more; volume of house 

 actually served by the hot and humid air sup- 

 ply, 1Y,000 instead of 20,000 cubic feet; hu- 

 midity maintained with comfort, over 60 per 

 cent., instead of 40 per cent. Another im- 

 portant factor, and there are yet more, is that 

 of house temperature. Unfortunately, Dr. 

 Ingersoll has omitted any mention of this; 

 but, judging from common American prac- 

 tise, one may, perhaps, assume a day tempera- 

 ture of 70°. Now in a Scots household, such 

 as the writer's, a temperature nearer 60° is 



thought more comfortable, and was that aimed 

 at in our experiments. And herein enters the 

 most interesting feature of the case, that the 

 weight of water present per cubic foot, and 

 hence the possible amount of dew deposit, is 

 approximately the same with 40 per cent, sat- 

 uration at 70° as with 60 per cent, saturation 

 at 60° ! Thus, after all, those at least of the 

 authorities that are European may not be so 

 far wrong in their estimate, and, truly, one 

 does like to say a little, if only occasionally, 

 in favor of the authorities. 



The writer would agree most heartily with 

 Dr. Ingersoll in the statement that any serious 

 effort to raise the indoor humidity is very well 

 worth while. 



Alan W. C. Menzies 



Obeklin, Ohio 



SCIENTIFIC BOOKS 

 The Purchasing Power of Money; Its De- 

 termination and Relation to Credit, Inter- 

 est and Crises. By Irving Eisher, assisted 

 by Harry G. Brown. New' York, The Mac- 

 miUan Company. 1911. Pp. xxii -j- 505. 

 Although Irving Eisher is a good propa- 

 gandist and can use arguments which appeal 

 to the man in the street, his reasoning is 

 based upon critical, logical, scientific analysis. 

 One of the propositions which he has recently 

 been actively promoting is international mon- 

 etary reform looking toward the elimination 

 or restriction of those disastrously wide varia- 

 tions in prices which may be due to the ir- 

 regularities of the world's gold production. 

 The principles upon which his suggestions 

 for regulating the general price level are 

 based are expounded in his " Purchasing 

 Power of Money." An early proficiency in 

 mathematics and interest in the mathematical 

 theory of prices has led him naturally to a 

 quantitative or quantity theory of money 

 which he builds up with a deep knowledge and 

 appreciation of scientific method. This atti- 

 tude is a justification for Science to show an 

 interest in his work which it could hardly ex- 

 hibit in the case of ordinary studies in eco- 

 nomies. 



