NOTICES OF BOOKS. 219 



attached to a rod of wood, and padded as above ; a sod should be 

 placed over the top of the tube, and the thermometer examined night 

 and morning. (I rarely in India found any difficulty in sinking a ther- 

 meter thus, at every encampment, though where the soil is very hard 

 it may not be possible to reach a greater depth than 1-2 feet.) If the 

 thermometers used as above are properly padded with cotton, it will 

 be found that their temperature will not, under ordinary circumstances, 

 alter for several minutes after they are withdrawn from the auger-hole 



or tube. 



X. Observations are much wanted on the temperature of the soil at 

 various depths beneath the snow during winter ; and on the tempera- 

 ture of the air and water between the under surface of melting snow- 

 beds, and the subjacent dormant vegetation, with the view of deter- 

 mining the causes of the rapidity with which plants germinate and 

 blossom after the disappearance of the snow from alpine situations. 



Jos. D. Hooker, 



May 2, 1857. Assistant Director, Royal Gardens, Kew. 



NOTICES OF BOOKS. 



An Introduction to Cryptogamic Botany; by the Rev. M. J. Berkeley, 



. • T "* 1»_- iL/k A lif llAH 



F.L.S. With 



Upwards of a century has now elapsed since Introductions to Botany 

 first appeared in a scientific form. In this, as in all other modes of 

 methodizing the study of plants, Linneeus successfully led the way ; 

 and of all his followers, those have made the greatest progress and ad- 

 vanced the study most who, having caught the spirit of the author of the 

 ■ Philosophia Botanica,' observe and study well, reason cautiously, and 

 rarely let their pens far outstep the limits of their own experience. Of 

 the numberless Introductions to Botany which crowd our library- 

 shelves, how few are ever consulted I scarcely a dozen rank higher than 

 more or less complete or skilful compilations ; and amongst those which 

 bear evidence of the author's having patiently exhausted all the attain- 

 able means of verifying his statements, few indeed show any amount of 

 originality, critical inquiry, aptitude for correlating facts and deducing 

 general laws, prescience of future discoveries, indications of researches 

 to be pursued that may open up the path to these, or warnings , ag oust 

 confounding realities with appearances. For the most part hey con- 

 sist of a resume of many of the fact, and many of the fables that have 







