SCIENCE 



[N. S. Vol. XXVIII. No. 724 



tion of the gas producer in combination -witli 

 the gas engine. The result in the first case 

 will shortly be known as the White Star Line 

 has taken this matter up and is building a 

 large vessel equipped with such engines. The 

 latter subject, however, although one of great 

 interest in view of what has been done with 

 the internal combustion engine, seems to war- 

 rant going deeper into the subject and has 

 led up to its consideration on shipboard in 

 connection with supplying gas for the use of 

 the engine. In treating of the gas producer 

 he not only speaks of the good features, but 

 tells of the difficulties, which are of consider- 

 able importance, one being the cleaning of the 

 fires and the other the replenishing of the 

 water to produce steam admitted to the fuel 

 when the vessel is in salt water. These are 

 subjects which the enthusiasts on the gas pro- 

 ducer have overlooked and will have to be 

 taken care of in its development. 



The questions from examination papers at 

 the end of the volume, although some of them 

 are unnecessary, for the proper care and man- 

 agement of the marine engine, such as " Define 

 the term ' the Latent Heat of Steam,' " there 

 are others which will be found valuable such 

 as " Explain how a boiler is liable to suffer 

 from undue haste in raising steam, and de- 

 scribe the precautions that are necessary when 

 steam is being raised." The man who has the 

 care of a steam engine should know all about 

 the management of the boiler and no doubt 

 will attend to his duties much better if his 

 head is not filled with latent ideas. 



Horace See 



New York, 



October 21, 1908 



Gray's New Manual of Botany. A Hand- 

 book of the Flowering Plants and Ferns of 

 the Central and ISTortheastern United States 

 and Adjacent Canada, rearranged and ex- 

 tensively revised by Benjamin Lincoln 

 EoBiNSON, Asa Gray Professor of System- 

 atic Botany in Harvard University, and 

 Merritt Lyndon Fernald, Assistant Pro- 

 fessor of Botany in Harvard University. 

 New York, Cincinnati, Chicago, American 

 Book Company. Seventh edition, illus- 



trated. Copyright, 1908, by the president 



and fellows of Harvard College. 



Sixty years ago Dr. Asa Gray issued the 

 first edition of his " Manual of the Botany 

 of the Northern United States," which covered 

 the region " from New England to Wisconsin, 

 and south to Ohio and Pennsylvania in- 

 clusive." In the second edition (1856) this 

 rather limited region was extended southward 

 so as to include Virginia and Kentucky, and 

 westward to the Mississippi River, and here 

 the boundaries remained for the third, fourth 

 and fifth editions. The sixth edition was 

 nominally " revised and extended westward to 

 the 100th meridian," but in fact did not 

 include all of the plants in the large addition 

 to its area. The westward range of the pres- 

 ent edition terminates at the 96th meridian, 

 and it thus includes the trans-Mississippi 

 states of Minnesota, Iowa and Missouri, and 

 small fractions of eastern Nebraska and 

 Kansas. 



To one who was " brought up " on Gray's 

 " Manual," this new edition has peculiar in- 

 terest, and while many changes have been 

 made in the old book the revisers have suc- 

 ceeded in preserving enough of the style of 

 treatment, and the general appearance to make 

 one soon feel at home in the new volume. 

 The first thing that one who knew the old 

 manual notices is the almost complete inver- 

 sion in the sequence of the families, the book 

 now following Engler and Prantl's " Pflanzen- 

 familien," instead of De Candolle's "Prodro- 

 mus." This brings it into harmony with most 

 modern systematic publications in this 

 country and Europe, and makes it much more 

 usable than it would have been had the old 

 sequence been continued. 



Another innovation is the introduction of 

 many illustrations (numbering more than a 

 thousand) which help to make the specific 

 descriptions more distinctive. These are 

 usually selected with much care, being used 

 only when they can certainly help the text. 

 Thus in the grasses (Gramineae) and sedges 

 (Oyperaceae) they are very freely used, as 

 they are also in Umbelliferae. 



In regard to nomenclature we are told that 

 the editors have scrupulously endeavored to 



