February 18, 1898.] 



SCIENCE. 



245 



of the cycle from time to time at any one point 

 on the earth's surface. Number (3) appears to 

 be true for every cycle except the annual and 

 diurnal cycles, and is the most difficult and con- 

 fusing condition that confronts the believer in 

 weather cyles. The formula 



is a mathematical expression of the sudden in- 

 version of phase which may take place in har- 

 monic curves, as is beautifully shown by Pro- 

 fessor Michelson's harmonic analyzer. Whether 

 this, however, has any relation to weather 

 curves is uncertain. 



I feel strongly that the difficulties will in 

 time be solved, and that forecasting by means 

 of weather cycles will supplant largely, if 

 not entirely, all other forms of weather fore- 

 casting. 



H. Helm Clayton. 



Blub Hill Meteorological Observatory, 

 Hyde Park, Mass., February 8, 1898. 



SCIENTIFIC LITER ATUBE. 

 The Ruins and Excavations of Ancient Rome. A 



Companion Book for Students and Travelers. 



By EODOLPO Lanciani. Boston and New 



York, Houghton, Mifflin & Co. 1897. Small 



8vo. Pp. xxiv+619. 



This book will be a godsend to the more in- 

 telligent class of English-speaking travelers, 

 who are not obliged to limit themselves to a 

 very short stay in Eome. Few, indeed, are the 

 persons who have not felt somewhat bewildered 

 when they have been called upon to map out 

 their time for a winter in the Eternal City so 

 as to use it to the best purpose. 



The ordinary guidebook, no matter how good 

 it maybe, is not enough ; Middleton's 'Ancient 

 Rome,' which is in many ways almost indis- 

 pensable, is written largely from an architect's 

 point of view ; the various German works are 

 for the most part intended more for professional 

 students of antiquity, and Professor Lanciani's 

 other two books, ' Ancient Rome in the Light 

 of Recent Discoveries ' and ' Pagan and Chris- 

 tian Rome,' are of too popular a character to 

 be very useful, if a person wishes to undertake 

 a serious, albeit a not strictly professional, 

 study of the ruins of the city. There was, 



therefore, need for just such a book, which 

 should cover substantially the whole field and 

 which should include the most recent results of 

 Roman topographical investigation, as the one 

 before us. Its usefulness will, however, by no 

 means be confined to intelligent travelers, 

 for, to quote from the preface, ' students wish- 

 ing to attain to a higher degree of efficiency in 

 this branch of Roman archaeology (viz. , topog- 

 raphy) will find copious references to the 

 standard publications on each subject or part of 

 a subject.' Indeed, the skill with which Pro- 

 fessor Lanciani has constantly kept in mind the 

 needs of these two classes of readers, without 

 thereby spoiling the unity of his book or mak- 

 ing it unfit for either class, is worthy of high 

 praise. The enormous mass of material which 

 must be handled in any treatment of Roman 

 topography has been arranged and presented 

 with simplicity and skill ; questions in dispute 

 have been indicated without lengthy discussion, 

 and thus the dryness so characteristic of works 

 in which the statement of a very large number 

 of facts is necessary has been in a great measure 

 avoided. 



In Book I. of his work, which contains 'gen- 

 eral information,' Professor Lanciani has gath- 

 ered together a large amount of material that 

 is not easily accessible. The geological forma- 

 tions about the city, the climatic conditions, 

 the quarries, the bricks and the Tiber are dis- 

 cussed. The walls in different periods, the 

 bridges, the aqueducts, the cloacse, the regions 

 of Augustus and the maps of the time of Severus 

 — what might, in fact, be termed the anatomy of 

 the city — are also treated here. Some interest- 

 ing statistics, too, in regard to population and 

 the amount of the water supply have been in- 

 cluded. Books II. and III. are concerned with 

 the very heart of the city — the Palatine Hill 

 and the Sacra Via from Coliseum to Capitol — 

 and here is included also the discussion of the 

 Forum Romanum and of the adjoining fora of 

 imperial times. In book IV. the rest of the 

 city is described according to the Augustan 

 Regions and there is a brief concluding chapter 

 on the 'general aspect of the city.' This is 

 followed by an appendix containing lists of the 

 Emperors, Popes and artists and useful infor- 

 mation touching chronology, weights and 



