November 18, 1898.] 



SGIENGE. 



713 



that is not shared by many students of nature. 

 As meteors are still coming to the earth, and 

 everyone has seen ' shooting stars,' the meteoric 

 hj'pothesis, by appealing to a process still in ac- 

 tion, by which the earth may have been formed, 

 is particularly attractive as a subject for popular 

 presentation. 



The chapter on the atmosphere contains not 

 only an instructive summary of some of the 

 leading facts concerning the outer envelope of 

 the earth, but, overstepping all stereotyped 

 methods, deals also with the changes which the 

 movements of the air, and the circulation of 

 water vapor in it, make upon the seas and lands 

 beneath. The freedom in this connection that 

 a popular essay seems to demand, is indicated 

 by the variety of themes embraced in this dis- 

 cussion of the atmosphere. These are ' whirling 

 storms ;' 'the system of the waters,' including 

 the waters stored in the earth or rock-waters, 

 the nature and origin of tides, the action of 

 shore waves, the character of sea beaches and 

 cliffs, etc. ' ocean currents,' their influence on 

 climate and on the distribution of life, and con- 

 nection with past geological changes ; ' the cir- 

 cuit of the rain;' 'the geological "' ' rk of water;' 

 under which falls the sculpturing of the land 

 by streams; and 'lakes.' Such a highly com- 

 plex group of subjects in a chapter of one 

 hundred pages, while not to be tolerated in a 

 systematic treatise on physiography, does not 

 seem out of place in a story book of nature. 

 Systematic works are apt perhaps to impress 

 one with the view that the operation of natural 

 forces are independent and stand alone, each 

 complete in itself, but a more general view, in 

 which their mutual dependence and interaction 

 are made prominent, is no doubt best for popu- 

 lar presentation. However comprehensive a 

 book may be, one essential is that facts and 

 principles should be accuratel5' stated. Here 

 enters one of the leading difficulties in popular 

 writing. For example, on page 101, in de- 

 scribing the ascent of warm air in circular 

 storms, the draft in a chimney is introduced as 

 an illustration, and the statement made that 

 ' the heated lower air breaks its way up the 

 shaft, gradually pushing the coolor matter out 

 at the top,' and, later, ' wherever the air next 

 the surface is so far heated that it may over- 



come the inertia of the cooler air above, it 

 forces its way up through it in the manner in- 

 dicated in the chimney flue.' Now, does the 

 warm air rise and force its way through the 

 cooler and denser air above, by reason of any 

 force inherent in itself ; is it not that the attrac- 

 tion of the earth is less, volume for volume, 

 for warm than for cold air ; the former being 

 forced to rise by the denser air following under 

 it and forcing it upward. 



In this same connection attention may be di- 

 rected to certain statements which, as the saying 

 is, would 'puzzle a mathematician.' In discussing 

 the flattening of the earth at the poles, page 82, 

 we read, ' the average section at the equator be- 

 ing about twenty-six miles greater than that 

 from pole to pole.' Again, in writing of the 

 rebound of a marble when dropped on the floor, 

 page 366, it is stated that the marble becomes 

 ' shorter in the axis at right angles to the point 

 which was struck;' also, on page 369, occurs 

 the statement that the ' movements of this wave 

 are at right angles to the seat of the originating 

 disturbance.' The italics are by the present 

 writer, and meant to emphasize the opinion that 

 these statements are unintelligible. 



One aim in popularizing science is to root out 

 superstitions and in their place, if possible, 

 substitute rational explanations. In this con- 

 nection Shaler strikes a blow at the time-hon- 

 ored 'Jack-o'-lantern' or ' Will-o'-the-V»lsp ' 

 which many of us have been looking for in vain 

 since childhood. This ancient spook needs to 

 have better credentials, or else forever disap- 

 pear from our swamps; or, more accurately, its 

 uncertain light should be dispelled from men's 

 fancies. 



The breadth of view and comprehensive char- 

 acter of the remaining essay on glaciers, the 

 work of underground water, the soil, etc., is 

 perhaps sufficiently indicated by the statements 

 just made in reference to the complex groups of 

 phenomena discussed in the chapter devoted to 

 the atmosphere. 



Throughout the book there is an aim to culti- 

 vate what has been termed the scientific use of 

 the imagination, or the power of forming men- 

 tal visions of the relations of matter, space, 

 time, etc., which are beyond the power of the 

 eye to grasp, and transcend daily experience. 



