LITERARY NOTICES. 



501 



are kept at the Observatory, and two Pro- 

 fessors of Mathematics were employed on 

 duties other than those of observing. 



Storms, their Nature, Classification', 

 AND Laws, with the Means of predict- 

 ing them by their Embodiments, the 

 Clouds. By William Blasids, for- 

 merly Professor of the Natural Sci- 

 ences in the Lyceum of Hanover. Phila- 

 delphia : Porter & Coates. Pp. 342. 

 Price, $2.50. 



This volume is an interesting contribu- 

 tion to the literature of an important branch 

 of meteorology. It is a result of many years 

 of observation, and the conclusion of the 

 author is that existing theories of the na- 

 ture and laws of changes of weather are in- 

 trinsically erroneous. Instead of an area 

 of barometric depression being the storm 

 itself, and the cause of the movement of the 

 air-current, the storm is the conflict of air- 

 currents of different temperatures, and the 

 barometric depression the effect of their 

 movement. Hence atmospheric appear- 

 ances and phenomena more truly indicate 

 and forecast storm-movements than does 

 the barometer. 



The air-currents arise primarily from 

 difference of temperature in the equatorial 

 and polar atmospheres, and in the upper 

 and lower regions of air. In the tendency 

 to restore and maintain the equilibrium 

 thus disturbed originate all the movements 

 known as storms. 



These movements will be L Vertical, 

 that is, between the lower and upper strata 

 of air. 2. Hoi'izontal, or between the poles 

 and equator. 



By these movements, in connection with 

 local circumstances, all modifications of 

 storms are produced. In temperate regions 

 the horizontal movement of storms is most 

 frequent the vertical most frequent and 

 violent in the tropics. 



The formation of a cloud tells us not 

 only that vapor is being condensed in the 

 air, but that warm and cool currents have 

 encountered each other. 



In the horizontal movement, the cold 

 and wai-m currents overlap each other, the 

 vapor -laden warm air from the equator 

 rising over the colder current. A conse- 

 quence is, the warm air ascends until its 

 waves reach an elevation where condensa- 



tion takes place along their crests, pro- 

 ducing flecks and bars of cloud-caps of the 

 aerial waves. These bars of cloud some- 

 times span the heavens, rising in the south- 

 ern horizon, heralding the approach of a 

 northeast storm. 



Not until these reach the zenith, says 

 the author, does the barometer annoimce 

 the approaching change. The storm-area 

 is where these opposing currents encounter 

 each other. The rotary theory of storms 

 he considers defective, and says that the 

 wind blows in all parts of a storm-area in 

 direct lines from the circumference to the 

 centre. So we encounter wind from differ- 

 ent directions as the storm passes. 



According to the author, observation 

 of the clouds, which are an embodiment of 

 the storm, affords earlier and more trusty 

 data of its approach than the barometer, 

 and the rules for navigators based on the 

 cyclone theory are worse than useless. The 

 theory that storms progress by working 

 their own way, that is, by condensation 

 and rainfall in their front, he says is like a 

 wheelbarrow drawing the man after it. 



The work is, in many respects, sugges- 

 tive, and will be read with interest. 



Progress-Report upon Geographical and 

 Geological Explorations and Surveys, 

 west of the One Hundredth Meridian, 

 in 1872, under the Direction of Briga- 

 dier-General A. A. Humphreys, Chief of 

 Engineers, U. S. A., by First-Lieutenant 

 George M. Wheeler, Corps of Engineers 

 in charge. , 



This thin pamphlet of some 55 pages is 

 really but a fragmentary sample of the long- 

 expected quarto report of the Government 

 surveys of this singularly wild and inter- 

 esting field. Thus a few specimen full-page 

 plates are given, especially of the weird-hke 

 canons ; also a map. The plan of compo- 

 sition is commendably judicious, in that it 

 avoids the journal form ; for although it 

 is much easier to sustain a certain sort of 

 interest by means of the narrative method, 

 yet in a scientific work such a form is in 

 great danger of unprofitable extension. 

 Still the story is told in a graphic way, with 

 the results classified, thus giving plan and 

 system, which are indispensable to scientific 

 work. As a sample of the best sort of 

 scientific work, for the reason that it is 



