200 



SCIENCE. 



[Vol. X. No. 246 



Two chapters are given to the study of the ' limitations of the 

 steam-engine,' a phrase of somewhat awkward form rhetorically, 

 but which is familiar to all engineers interested in the subject as 

 relating to the limits set to the efficiency of the machine by the 

 counteracting influences of ' cylinder condensation," — another awk- 

 ward phrase, meaning condensation of steam in the steam-cylinder, 

 — and of conduction and radiation or other forms of waste which 

 distinguish the actual from the ideal engine. Here the author takes 

 the hitherto unconquered bull by the horns, and gains the honor of 

 having been the first to produce a rational formula embodying what 

 are supposed to be the laws of this method of transmission of heat, 

 and of loss of engine efficiency due to it. The resulting expression is 

 somewhat complicated ; but it is justified by experiment, so far as 

 comparison has been carried by its author, and may be expected to 

 stand until further progress is made in investigation of the actual 

 conditions, — which are unquestionably far from being few or unin- 

 volved, — and extended research shall have thrown more light upon 

 a problem which is to-day the most important in the whole theory 

 of the steam-engine. 



Space does not permit the criticism in detail of this or of any 

 other part of the book. It is rich in valuable material, and al- 

 though, like the angels, not absolutely without fault, in the opinion 

 of well-informed engineers, either in matter or in manner, deserves 

 exceptionally high praise for its wealth of excellences. 



The Ancient Cities of the New World. By DfiSIRfi Charnay. 

 New York, Harper. 8°. 



In the present volume Desire Charnay gives the results of his 

 long and careful explorations in Central America, which were begun 

 in 1857. Since that time, all his energies have been directed to- 

 wards the collection and preservation of the antiquities of that 

 country. As the expenses of his expeditions were defrayed in part 

 by the French Government, in part by an American citizen, Mr. P. 

 Lorillard, his collections are deposited in the Trocadero in Paris, 

 and in Washington : they are indispensable for all future studies of 

 the culture of ancient Central America. The book under review is 

 as well pleasant to read — describing, as it does, the travels of the 

 author and the present state of the country — as of scientific value, 

 giving the results of his studies, and showing in numerous splendid 

 illustrations the ancient monuments and other kinds of relics, as 

 well as beautiful views and characteristic groups. 



It was the main object of the expedition with which the author 

 was intrusted to collect authentic material for a thorough study of 

 the ancient civilization of Central America : therefore his studies 

 were almost exclusively directed to the collecting of relics, photo- 

 graphing of buildings and reliefs, and making casts of the inscrip- 

 tions and bas-reliefs. The material he gives in this line cannot be 

 excelled. His researches lead him to the conclusion that the 

 American civilization at the time of the conquest was of compara- 

 tively recent origin. It is his opinion that all its branches bear the 

 characteristics of Toltec civilization, and that, by studying the monu- 

 ments, the migrations and the gradual development of Toltec art 

 may be discovered. A map shows the author's opinion regarding 

 the subject. He lets the prehistoric Toltecs immigrate from the 

 north-west. From the plateau of the City of Mexico two branches 

 emigrated, — the Gulf branch and the Pacific branch. Subdivisions 

 of the former invaded Yucatan. He lets the two principal divis- 

 ions meet in Copan, the south-eastern terminus of their migrations. 

 " The Toltecs," he says, " migrated south, following the coasts of both 

 oceans. They ceased to exist as a nation after the disruption of 

 their empire ; but their scattered remnants carried on the work of 

 civilization in Central America, on the high plateaus, and in 

 Anahuac, evidenced in the strong resemblance that the civilizations 

 of these various regions bear to one another." The time of the 

 erection of the largest buildings and temples he supposes to be about 

 the twelfth century. 



We cannot accept those theories of the author referring to the 

 connection between the art of eastern Asia and Central America. A 

 thorough and detailed comparison has never been made, and super- 

 ficial similarities of monuments and customs cannot be a sufficient 

 proof of a common origin. 



Since the present volume was written, the author has accom- 

 plished a new journey to his favorite field of explorations, a pre- 



liminary report of which is being published in Le Tour dit Monde 

 and in the Globus. The recent enterprise of this devoted explorer 

 has not been less successful than the former ones, some results of 

 which are fortunately made accessible in the volume just published. 



Living Lights. By CHARLES FREDERICK HOLDER. New York, 

 Scribner. 12°. 



Mr. Holder has thrown into a popular form the substance of 

 what is known about phosphorescent animals, illuminated by oc- 

 casional coruscations of imagination. Most of his readers will be 

 surprised to learn that the power of emitting light is so widely 

 shared by animals of all classes. Not only do fire-flies fly, glow- 

 worms glow, and zoophytes twinkle in the sea, but sea-anemones, 

 alcyonarians, gorgonias, star-fishes, earth-worms, crabs, shell-fish, 

 lizards, frogs, toads, fishes, birds, monkeys, and men must be added, 

 according to Mr. Holder, to the number of animals capable of giv- 

 ing forth light. In the author's preface, he says, " In the United 

 States there are ten thousand enrolled young naturalists, compris- 

 ing the Agassiz Association. As one of a committee solicited to 

 answer questions propounded by the young people, ... I have 

 often been surprised at the nature of the queries, which shows that 

 this army of young observers includes many who are not merely 

 collectors of curiosities, but are naturalists in the best sense. They 

 are systematic inquirers, and working in the right direction to be- 

 come scientists, should they continue. It is to these young scien- 

 tists . . . that this volume is addressed." While we welcome any 

 book that will serve to awaken in the young an earnest desire to 

 study nature, and while this fascinating volume will certainly awaken 

 interest, it is all the more to be regretted that the author is so fond 

 of pyrotechnical natural history. He loves to hear the sigh of 

 pleasurable surprise that rises from his audience as he sets off a py- 

 rosomatic rocket, or kindles pavonian flame. This fault appears es- 

 pecially in the illustrations, which, for young people, should be accu- 

 rate, since from them they derive their lasting impressions. Not to 

 rely on our own judgment, we quote the author's own words, " It 

 is evident that illustrations of the phosphorescence of marine animals 

 must be more or less conjectural ; " and again (the Italics are ours), 

 " In Plate XXVII. [XXVI.?] an ideal \'vf^ is given of X\\e. possible 

 appearance of the light of a large heron." There is no excuse for 

 ' conjectural illustrations ' and ' ideal views of possible appearances ' 

 in a book of this nature. They are distinctly misleading and 

 wrong, and have the obvious and inevitable effect of throwing dis- 

 credit on some of the more highly-colored portions of the text, into 

 which the phosphorescence of herons, lizards, monkeys, and men 

 seems to have been admitted on very slender evidence. Those por- 

 tions of the book which record the results of Mr. Holder's own 

 observations are the most interesting, and perhaps the least illu- 

 mined by fancy. 



The Ventilation and Warming of School-Buildings. By GIL- 

 BERT B. Morrison.' New York, Appleton. 8°. 



It seems a long leap from Rosenkranz's ' Philosophy of Educa- 

 tion,' which opened the International Education Series, to this suc- 

 cessor, which discusses practical schoolhouse-building. But Dr. 

 Harris shows how catholic his conception of education is by in- 

 cluding the two books in the same series. 



Mr. Morrison truly says that no "subject has been more carefully 

 and intelligently studied than the direct and ultimate effects of im- 

 pure air on the human system, and on no subject is there more 

 unanimity of competent opinion " (p. 18) ; but nevertheless the want 

 of sufficient and definite information regarding the ventilation of 

 schoolhouses is general. The lack of general information on 

 this particular point is the more blameworthy, inasmuch as the 

 effects of breathing impure air are not only pathological, but peda- 

 gogical and economic. The author instances this (p. 22). 



A short chapter deals succinctly with the physical aspects of the 

 air, and then the various tests for its examination are briefly de- 

 scribed. The general theory of ventilation is illustrated by a simple 

 experiment (p. 47) ; and then the natural and artificial methods of 

 ventilation are discussed with more attention to detail. The remain- 

 ing chapters discuss the general problems of ventilating and heat- 

 ing, and include descriptions of many of the expedients that are 

 used for these purposes. The treatment of each question is abreast 



