264 



SCIENCE. 



[Vol. XV. No. 377 



to furnish at moderate cost a brief course in note-reading for 

 the smaller village and country schools, in which a full graded 

 course cannot well be followed. 



— Dr. Francis Warner (physician to tlie London Hospilal, etc.) 

 has prepared for publication his lectures on " The Growth of In- 

 tellectual Faculty,'" delivered for the Teachers' Training Syndicate, 

 in Cambridge, during the Lent term in 1888 and 1889. The author 

 insists on the necessity of observing physical facts, their causes 

 and effects, when considering mental and moral questions, and 

 has worked out a system of ob?er\ing pupils in school. Special 

 attention is given to such states as " attention," nervousness, sleep, 

 fidgetiness, disobedience, lying, headache, low development, etc. 

 Observations made in schools are largely referred to, and the 

 notes of many cases are given. The book, which is illustrated 

 with diagrams, will be issued shortly by Macmillan & Co. 



— A year or two ago. a series of articles was published in The 

 Forum, entitled "How I Was Educated.'' The contributors were 

 presidents of univei'sities and colleges, other prominent educators, 

 and men of letters. These autobiographical papers were collected 

 and printed in a separate volume, and now belong to the standard 

 educational literature of (he United States. A new series of ar- 

 ticles will appear forthwith on an analogous question: viz., 

 '■What were the influences — the persons, the circumstances, the 

 books — that have operated most to form the character and occu- 

 pation of a number of notable scholars and men of letters and 

 science?" The contributors to this series will include eight or 

 ten of tlie foremost men of letters, men of science, teachers, and 

 statesmen, American and foreign. 



— Dr. E. N. Sneatb, lecturer on the history of philosophy at 

 Yale, has been inspiring the preparation of a series of small vol- 

 umes of selections from the leading philosophers from Descartes 

 down, so arranged as to present an outline of their systems. 

 Each volume will contain a biographical sketch of the author, a 

 statement of the historical position of the system, and a bibliog- 

 raphy. Those so far arranged for are •■ Descartes," by Professor 

 -Ladd of Yale; "Spinoza," by Professor Fullerton of the Univer- 

 sity of Pennsylvania: "Locke," by Professor Russell of Williams; 

 " Berkeley," by Ex-President Porter of Yale: "Hume," by Dr. 

 Sneath of Yale: and "Hegel," by Professor Royce of Har- 

 vard. Kant, Comte, and Spencer will certainly be added to the 

 series, and others if encouragement is received. The publishers 

 will be Henry Holt & Co. 



— Mr. D. C. Thomson, author of "The Life and Works of 

 Thomas Bewick " and " The Life of H. K. Browne, ' Phiz,' " has 

 had in preparation for the past three years an important work on 

 the Barbizon School of Painteis. This volume will be similar in 

 size (quartoj and character to the " Lif? of Bewick" and the 

 " Life ot • Phiz,' " and will be illustrated with numerous plates 

 and wood-engi-avings. The work will supply a complete bio- 

 graphical and critical account of the group of five celebrated 

 French painters known as the Barbizon School, —Theodore Rous- 

 seau, Jean Francois Millet, Narcisse VirgiliQ Diaz, Charles Fran- 

 gois D'Aubigny, and Jean Baptiste Camille Corot. Such a publi- 

 cation necessarily demands excellent illustrations; and many 

 representations will be given of pictures, drawings, and portraits, 

 in various methods of reproduction, — etching, photogravui-e, 

 wood-engraving, etc. It is proposed to publish the volume by 

 subscription, which should be forwarded to Scribner & Welford, 

 New York, without delay. 



LETTERS TO THE EDITOR. 



*+* Correspondents are requested to be as brief as possible. The writer's name 

 ■is in all cases required as proof of good faith. 



The editor ^odl be glad to publish any queries consonant with the character 

 of the journal. 



On requfst, twenty copies of the luimber containing his communication will 

 ■be furnished free to any correspondent. 



The Psychrometer. 



There have recently appeared two quite extended investiga- 

 tions on the use of the psychrometer (wet and dry bulb thermom- 

 eters) in determining the moisture-contents of the air. The first 

 is a comparison with the condensing hy grometer, made by Pro- 



fessor S. A. Hill of Allahabad, India, published in the Journal of 

 the Asiatic Society of Bengal {wo\. vii., 1888). Recent investiga- 

 tions in this country have shown the entire uselessness of trying 

 to obtain reBned results with an unventilated psychrometer, and 

 we note that a partial neglect of this precaution has led to wrong 

 inferences in this paper. The experiments with the Regnault ap- 

 paratus revealed the same difficulties, with the plate, fumes of 

 ether, etc., that have been noted by others. The ccimparifons 

 were made with artificial ventilation, as well as in a breeze and 

 in still air, at pressures ranging from 20.6 to 39.4 inches. There 

 were twenty-seven observations; and of these, four had an arti- 

 ficial ventilation. The method of ventilation is not given, but we 

 may assume that it was sufficient to give good readings. The 

 following are the results: — 



The results given in the last two columns are most extraordinary. 

 There is almost a perfect accordance between the dew-point ob- 

 served at heights up to 6, .500 feet and that computed for a height 

 of 600 feet from the ventilated psychrometer. Without more in- 

 formation as to the accuracy of the condensing hygrometer and 

 the sufficiency of the ventilation, it would be dangerous to argue 

 upon these results; bat the coincidence between them and those 

 obtained in this country by the writer up to 3,000 feet is very 

 remarkable. Professor Hill, by combining together all the ven- 

 tilated and unventilated readings, obtains an exactly opposite 

 result, but it is now known that unventilated psychrometer read- 

 ings are worthless for careful comparison. 



The second paper is by Dr. Haldane and M. S. Pembrey of Ox- 

 ford, England. It is to b^ound in the Philowphical Magazine, ' 

 April, 1890, pp. 306-831. In this paper an attempt is made to 

 compare the unventilated psychrometer with determinations of 

 moisture by chemical methods. The experimenters have given 

 the chemical method an exhaustive study, and their results in 

 that line are excellent. The comparisons with the psychrometer, 

 twelve in number, are unsatisfactory and lead to erroneous con- 

 clusions for the reason already given. Five out of the total were 

 made in so damp an air that they cannot help in the comparison. 

 The other seven are as follows: — 



In column (4) are given vapor pressures computed by Glaisher's 

 Tables, as published in Guyot's Tables, 1884. It is very gratify- 



