CONTENTS. IX 



of Small Precipitation on eacli side of the Equatorial Belt, 197. Sub-tropical Zones 

 of Precipitation, 197. Regions of Constant Rain.s, 198. — Conditions affecting 

 the Distribution of Precipitation, 198-203. Interiors of large Continental 

 Masses, dr\', 199. Regions of abnormally large Precipitation, 199. Distribution 

 of Pain and .Snow on Mountain Panges, 200. The :Monsoon Winds, 200, 201. — 

 Climatic Condition of the Region east and south of the Mediterranean dis- 

 cussed, 201-203. Faniiiios in India (note), 201. Wojeikof on tlie Climatic 

 Peculiarities of the Saliara, 201, 202. Distribution of Rain and Snow in the Po- 

 lar Regions, 203. Conditions favoring Precipitation in the form of Snow, 204. 



SECTION V. 



Has the Extent of Land Surface on the Globe been, on the whole, in- 

 creasing WITH the Lap.se of the GEOLOGICAL Age 203-219 



The Continental Masses have, with tlie Lapse of Geological time, been growing 

 larger, 205. Reference to the IMaps of Delesse, 206. Manner in whicli Detri- 

 tal Materials accumulate, 207. How tlje Continents have been built up, 207, 

 208. A Gain of Land tlie Xecessary Result, 208. Permanence of the Ocean 

 inferred from its great depth, 209. Stability of the Continents a necessary conse- 

 quence, 207. Mean Elevation of the Land Masses of the Globe, 209. Persist- 

 ence of Areas of Elevation and Depression first enunciated by Dana, 200. Geo- 

 logical Growth of Nortli America, 211 ; of Asia, 211. Foster and Whitney, quoted, 

 211. — Evidence of the Stability of the Oceanic Areas derived from the 

 Character of the Sea Bottom, 214-216. Investigations of Agassiz, 214. 

 Views of A. Geikie and W. 11. Carpenter, 215. Summary of the Evidence, 216. 

 — Inquiry whether the Increase of the Continental Masses is SufEcieut 

 Cause for the Desiccation proved to have taken place, 210-219. I'rcjbaljlc 

 Effects on precipitation of Changes, in the form of the Land Ma.sses, 217. Higher 

 temperature suggested as a cause of former Greater Precipitation, 218. 



SECTION YL 



Examination of the Evidences of former Changes of Temper.ature on the 

 Earth. Has the Solar IIadi.xtion been diminishing in Intensity dur- 

 ing all or any portion of the Geological Periods? 219-257 



The term Geological Climates defined, 219. Tlie Glacial Epoch usually consid- 

 ered the only Cliiuatic Phase of importance, 220. — Investigation of Temperature 

 Changes during the Historic Period, 221-240. Difficulty of procuring proof of 

 Diminished Riiin-fall by means of Instrumental Observations, 222. Range of rain- 

 fall in various Regions, 222. Easier to determine the Mean Temperature than the 

 Meau Precipitation, 223. How far back do Records of Instrumental Observations 

 extend? 223, 224. When the Thermometer began to be regularly observed, 224. 

 Serious source of error in Thermometrical Observations not noticed until 1817, 

 224. Arago's investigations of the Mean Temperature at Paris, 224, 225. Loomis 

 and Newton's investigations of the Mean Temperature at New Haven, 225, 226. 

 Smithsonian Observations worked up by Schott, 226. Plantamour's investigations, 

 227. Dove and Quetelet cited, 227. Glaisher's Results near London examined, 

 227, 228. Summary, 228, 229. — Examination of Historical Records of Cli- 

 mate, not instrumental, 229-241. Arago's investigations examined and criticised, 



