350 



SCIENCE. 



[Vol. V., No. 116. 



It gives almost at the start a short treatment, 

 much shorter than Daniell's, of simple harmonic 

 motions ; and it devotes several pages to the 

 idea and theorems of potential. The subject 

 of air-pumps, and with it much that is wont to 

 make the student miserable, is dismissed after 

 a treatment of four pages. In the chapters 

 devoted to heat we miss the familiar names of 

 Dulong and Petit, and the other pre-Regnault 

 investigators of the phenomena of expansion. 

 The steam-engine occupies one page, without 

 an illustration. Carnot's cycle, with related 

 matters, fills ten pages. 



The book is written with great care. Its 

 language is clear and judicious. There are, 

 of course, slight inaccuracies. For instance : 

 the first sentence of article 26 reads as if a 

 point could be located by means of its distance 

 from any one plane. Again : on p. 209 we 

 find it stated as having been demonstrated ex- 

 perimentally by Joule, that, ; ' when a gas 

 expands without performing external work, it 

 is not cooled ; " the later experiment of Joule 

 and Thomson, which led to a different conclu- 

 sion, not being mentioned. 



From beginning to end, this volume of 

 Anthony and Brackett grapples with difficult 

 principles boldty and in good faith, as if the 

 authors expected their whole book to be read 

 and mastered. Trigonometry is freely used, 

 and occasionally something that borders on the 

 calculus. The long experience of the authors 

 as teachers encourages the hope that they have 

 not over-estimated the capacity of college 

 classes ; but, excellent as is the matter and 

 the manner of the book, one fears that the 

 ordinaiy student will find portions of it for- 

 midable. 



Perhaps it should not be otherwise. Cer- 

 tainly the extraordinary student, who craves 

 strong meat, will find it here, and of the best. 

 So small a book cannot teach all there is to 

 learn : it is not intended to do so. It does 

 not show the whole of physics, but it shows 

 ph}'sics as a whole. 



NOTES AND NEWS. 



During the opposition of Neptune just passed, 

 Professor Pickering continued the observation of the 

 planet's magnitude with the meridian photometer of 

 the Harvard-college observatory in the same method 

 as previously employed. Nine series of observations 

 extend from Dec. 16, 1884, to Jan. 21, 1885, the final 

 result from which, when corrected for atmospheric 

 absorption, instrumental error, and reduction to mean 

 opposition, becomes 7.63. The residual difference 

 for only one series is as great as two-tenths of a mag- 



nitude. The corresponding results for two previous 

 seasons are 7.71 and 7.77. Contrary to the experi- 

 ence of Mr. Maxwell Hall of Jamaica, who found 

 evidence for a rotation-period of Neptune in small 

 variations of the planet's light according to his own 

 observations, Professor Pickering regards it as im- 

 probable that there is any variation in the light of 

 Neptune of a strictly periodic character, and further 

 calls attention to the influence, much neglected by 

 observers, upon the observed brightness of objects 

 when seen east and west of the meridian on the 

 same night. This has to be taken account of in 

 the observations of maxima and minima of many 

 variable stars, and may to some extent account for 

 the variations of Neptune's light detected by Mr. 

 Hall. 



— Prof. Charles E. Bessey writes to the American 

 naturalist that fifteen years ago there were no dande- 

 lions in the Ames flora (in central Iowa) : now they 

 are very abundant, and have been for half a dozen 

 years. Then there were no mulleins: now there are 

 a few. Then the low and evil-smelling Dysodia chrys- 

 anthemoides grew by the roadside in great abun- 

 dance: now it is scarcely to be found, and is replaced 

 by the introduced * dog-fennel ' (Anthemis cotula). 

 Then the small fleabane (Erigeron divaricatum) 

 abounded on dry soils : now it is rapidly disappearing. 

 Then no squirrel-tail grass (Hordeum jubatnm) grew 

 in the flora: now it is very abundant, and has been 

 for ten years. Then there was no burr-grass in the 

 flora : now it is frequently found, and appears to 

 be rapidly increasing. Both of these grasses have 

 apparently come in from the west and north-west. 

 Fifteen years ago the low amaranth (Amarantus 

 blitoides) was rather rarely found : now it is abundant, 

 and has migrated fully a hundred and fifty miles 

 north-eastward. This plant has certainly come into 

 the Ames flora from the south-west within the last 

 twenty years. Old settlers say that there have been 

 notable migrations of plants within the past twenty 

 or thirty years. The buffalo grasses of various kinds 

 were formerly abundant in the eastern part of the 

 state: now they have retreated a hundred to a hun- 

 dred and fifty miles, and have been followed up by 

 the blue-stems ( Andropogon and Chrysopogon). The 

 blue-stems now grow in great luxuriance all over 

 great tracts of the plains of eastern Nebraska, where 

 twenty years ago the ground was practically bare, 

 being but thinly covered by buffalo grasses. In 

 Dakota it is the same : the blue-stems are marching 

 across the plains, and turning what were once but 

 little better than deserts into grassy prairies. 



— A principle that may generally be wisely adhered 

 to by reviewers is that notices of books appearing in 

 numbers should not be based on the first number 

 issued ; but this can be safely departed from in an- 

 nouncing the preparation of a new (fourth) edition 

 of Meyer's ' Konversations lexikon,' of which the 

 first part appears with imprint of 1885. Sixty-four 

 pages carry it to ' Absteigung.' Abyssinia is allowed 

 six and a half pages, which include liberal reference 

 to sources of information, an essential in all good 

 encyclopaedias. Among the illustrations there are 



