426 The National Geographic Magazine 



He opposes the nebular theory of the 

 earth's origin and asserts instead the 

 " planetesimal" hypothesis. Accord- 

 ing to this theory, "the earth, and the 

 moon as well, have grown by slow ac- 

 cretion, or infall, of small, cold, discrete 

 particles (planetesimals), which formed 

 the earth-moon ring or zone. The ocean 

 and the atmosphere have slowly accu- 

 mulated from the gases originally held 

 in the planetesimals, being forced to the 

 earth's surface by interior consolidation 

 due to gravity. The heat of the earth's 

 interior is, under this theory, due to 

 gravitational compression similar to the 

 production of the sun's heat." The 

 oceanic stage was leached long before 

 the earth attained its present size. To 

 summarize, the Chamberlin school be- 

 lieve that the outside of the earth has 

 always been cold, and that the heat 

 inside is due to gravitational compres- 

 sions. The nebular theory is that the 

 globe was once a fiery mass. The out- 

 side has cooled, but the inside is still as 

 hot as it was eons ago. The planet- 

 esimal theory is unsettling some long- 

 accepted theories of geology. 



Geography of Commerce. By Spencer 

 Trotter. With man3' maps and illus- 

 trations. Pp. xxiv + 410 5}4 x 8 

 inches. New York : The Macmillan 

 Co., 1903. $1. 10 net. 

 As the author very correctly remarks 

 in the preface of this volume," The un- 

 related facts of commerce have slight 

 educational value ; the}' should be made 

 to illustrate some underlying principle, 

 to make clear a natural law, to stand in 

 relation to the great stream of causes 

 and effects." Dr Trotter has kept this 

 principle in mind while writing his com- 

 mercial geography ; when he describes 

 the great business centers or the princi- 

 pal producing areas of the country, he 

 invariably explains what causes, physi- 

 cal, political, etc., make them promi- 

 nent. The result is he has produced a 

 book that not only describes the special 

 industries and occupations of the various 



sections of the United States and of the 

 world, but also imparts a great man}' 

 facts about the physical and political 

 geography of the countries. The illus- 

 trations, diagrams, and references are 

 admirably chosen. The one serious 

 criticism that might be made of the 

 volume is that the author has tried to 

 include too much information ; his chap- 

 ters sometimes resemble condensed cyclo- 

 pedic articles ; the style is also heavy, 

 so that while the book will be a useful 

 help to the teacher it may prove rather 

 dull for the pupil. 



The Philippine Islands, J493-J803. Ex- 

 plorations by earl}" navigators, de- 

 scriptions of the islands and their 

 peoples, their history, and records of 

 the Catholic missions, as related in 

 contemporaneous books and manu- 

 scripts, showing the political, eco- 

 nomic, commercial, and religious con- 

 ditions of those islands from their 

 earliest relations with European na- 

 tions to the beginning of the nine- 

 teenth century. Translated from the 

 originals (Spanish, French, Italian, 

 Latin, etc.), many of which are now 

 published for the first time. Edited 

 and annotated by Emma Helen Blair, 

 A. M., of the State Historical Soci- 

 ety of Wisconsin, assistant editor of 

 The Jesuit Relations and Allied Docu- 

 ments, and James Alexander Robert- 

 son, Ph. B., with historical introduc- 

 tion and notes by Edward Gaylord 

 Bourne, Professor of History in Yale 

 University ; also a full bibliography 

 and analytical index. With maps, por- 

 traits, and other illustrations. Fifty- 

 five volumes, large 8vo, about 325 

 pages per volume. Cleveland, Ohio: 

 The Arthur H.Clark Company. 1903. 

 $4.00 7/1?;' per volume. 

 The purpose of this magnificent series 

 of volumes is to place within reach of 

 the American public the most important 

 of the hundreds of manuscripts, letters, 

 and documents relating to the Philippine 

 Islands and written between 1493 and 



