Maech 28, 1902.] 



SCIENCE. 



511 



To meet this demand, a thermostat was 

 devised, of which a description will shortly 

 appear in the Journal of Physical Chemistry. 

 The regulator of this instrument functionates 

 so perfectly that the temperature can be kept 

 continuously at the same thousandth of a 

 degree for hours at a time. It is so con- 

 structed moreover as to be capable of adjust- 

 ment, within one or two hundredths of a 

 degree, to any desired temperature over a 

 range of about fifty degrees. 



The most important factors which make 

 such fineness of regulation possible are the 

 following : 



1. An extremely efficient circulation in the 

 bath, which eliminates all local differences of 

 temperature large enough to be readable. 



2. Such a construction of the regulator that 

 the expansive medium feels each minutest 

 change of temperature and reacts promptly to 

 it. 



3. Provision for supplying the bath at all 

 times with just the amount of heat needed, 

 and no more. The regulation does not con- 

 sist in alternately admitting and shutting off 

 the inflow of heat, but in a 'throttling' of the 

 same. 



The extreme accuracy of function men- 

 tioned above is naturally obtained only when 

 the thermostat is shielded from sudden 

 changes of radiation. But excellent results 

 are possible without such protection. Without 

 the use of any insulation whatever, the bath 

 can be held at a temperature of thirty or forty 

 degrees within a hundredth of a degree. 



W. P. Bradley. 



Wesleyan Univeesitt. 



scientific nomenclature. 



To THE Editor of Science: In Science for 

 March 21, I find an article on 'Scientific No- 

 menclature,' by Mr. Frank W. Very, which 

 concludes with the following words: 



Scientific descriptions remain unintelligible to 

 the lazy man who hates to use the dictionary. 

 They are free property to all who are willing to 

 take this trouble. 



On other pages of Science for March 21 

 (pp. 458 and 459), I find the words 'ecology' 

 and 'ecological.' As I had never seen them 



before, I said to myself: 'Here is my chance 

 to vindicate Mr. Very's judicious hint about 

 the lazy man and the dictionary.' So I turned 

 to the Century dictionary, but did not find 

 ecology or ecological. I next had recourse to 

 the new English dictionary of Murray, with- 

 out success, and then to the new edition of 

 "Webster, published the present year. None of 

 these contain the words above mentioned. Ke- 

 course to Liddell & Scott's Greek lexicon was 

 equally unavailing. I am moved, therefore, to 

 ask you for an explanation of this new term. 

 Horace White. 

 New York, 



March 22, 1902. 



[Ecology has doubtless been coined from 

 the same word as economics, being the branch 

 of zoology or botany that is concerned with the 

 dwelling place or distribution of animals or 

 plants. It will probably come as a shock to 

 biologists to learn that this word is not to be 

 found in recent dictionaries, as it is used in 

 elementary books and courses. The word ap- 

 pears to be post-Darwinian; perhaps some 

 reader can tell us when and where it was first 

 used. — Editor.] 



BOTANICAL NOTES. 



A POPULAR BOOK ON TREES. 



Whatever tends to popularize a knowledge 

 of our trees is to be commended. Any book 

 which induces a considerable number of peo- 

 ple to give more attention to the structure and 

 liabits of trees deserves our hearty approval. 

 It is true that too often these popular books 

 are so full of blunders that the scientific man 

 is constantly irritated as he runs over the 

 pages, and as a consequence lie is too often 

 unable to see the great body of valuable mat- 

 ter hidden beneath the superficial errors. We 

 have had within the last year or two a num- 

 ber of useful books dealing with plants of 

 various kinds from mushrooms and ferns to 

 wild flowering herbs, shrubs and trees. Now, 

 another book is brought out by Knight and 

 Millet, of Boston, under the title of 'Studies 

 of Trees in Winter,' by Annie Oakes Hunt- 

 ington, with an introduction by Professor- 

 Sargent. The fact that so eminent a botanist 



