Januaey 17, 1896.] 



SCIENCE. 



103 



this region by similar delays, and their life 

 blood extracted by the polite but very costly 

 exchange of ' gifts. ' Monteil had learned a 

 lesson from their experience, and, secreting suf- 

 ficient means to carry him through, 'played 

 poor.' The consequences were evident in the 

 great privations to which he was subjected for 

 some time after this. At length his opportunity 

 arrives, a caravan is ready to leave. He makes 

 the sheik a series of presents as farewell gifts, 

 which greatly embarrass that individual to 

 properly and adequately return, which was his 

 ^ immediate duty. The tide was turned in his 

 favor, and he got everything he wanted, and 

 thus escaped this new species of danger with 



He speaks very caustically of the rotten and 

 shaky condition of the affairs of Bornu, of which 

 state Kukawa is the chief city. It took only a 

 few months for his prediction of the fall of this 

 empire to be verified. 



On August 15, a year after leaving the Niger, 

 he starts on the jovirney to Tripoli. The cara- 

 van of 78 camels, 7 horses, 30 men and 30 slaves 

 must have presented a fine appearance, and 

 their minds must have been much lighter as 

 they started upon the last stage of their trip. 

 Aside from the discussion of the usual tribula- 

 tions of the long journey over the Sahara, and a 

 rather pathetic description of the evil works of 

 the ' demons of the desert who lead travelers 

 astray,' nothing novel is given in this part of 

 the book. 



On December 10, 1892, he reached Tripoli, 

 where his troubles were over. He was wel- 

 comed in France in the most cordial and well- 

 deserved manner. His promotion, his medals 

 and other honors have certainly been well 

 earned, and they grace a hard-working, earnest 

 and modest man. The volume contains much 

 more valuable material than is usually found in 

 a book of travels, particularly when written by 

 one who is rather more of a military man and 

 diplomat than a scientist. W. L. 



■A Laboratory Course in Experimental Physics: 

 By W. J. Loudon and J. C. McLennan. 

 Macmillan & Co. 8vo., 300 pp. Price, 



_ $1.90. 



This book is written by the Demonstrater and 



the Assistant Demonstrater in Physics in the 

 University of Toronto, and it is evidently de- 

 signed to meet the special requirements of stu- 

 dents in that institution. It is divided into two 

 parts, constituting an elementary course and 

 ' an advanced course. Part I includes a brief 

 treatment of length-measuring instruments, 

 vernier, cathetometer, spherometer, etc., which 

 is followed by some exercises in density deter- 

 minations, experiments with pressure and vol- 

 ume of gases and a little about capillarity. The 

 remainder of the elementary course is mostly 

 given to geometrical optics, although there is 

 something of a treatment of photometry and a 

 few exercises in specific and latent heat. The 

 second part treats of acoustics, heat, electricity 

 and magnetism, with a short appendix on 

 gravity and the pendulum. An elementary 

 knowledge of dynamics and the calculus is as- 

 sumed in the advanced course. In the various 

 experiments described it is generally assumed 

 that a perfectly adjusted piece of apparatus is 

 at hand ready to be set going. The instru- 

 ments figured and described in the ' acoustics ' 

 are from the atelier of Rudolph Koenig, and 

 nearly all of the illustrations in the book ap- 

 pear to have been made from perfectly con- 

 structed and finished apparatus. It is generally 

 admitted that a large part of the value of the 

 training in a physical laboratory comes from 

 experience in designing, constructing and ad- 

 justing apparatus for definite purposes. In no 

 other way can a student so quickly and thor- 

 oughly learn the sources of error entering into 

 an experiment, or the methods of eliminating 

 them and in a general way become familiar 

 with the limits of accuracy to which he is re- 

 stricted. Viewed from this standpoint, such a 

 system as seems to be implied in this book is 

 not to be commended. In fact, it is a little 

 diflScult to know under what conditions this 

 book is intended to be used. The authors say 

 in the preface that it owes its origin to the ' difii- 

 culty experienced in providing, during a lim- 

 ited time, ample instruction in the matter of 

 details and methods ' ^ * ^^ 'at the present 

 day, when students are required to gain knowl- 

 edge of natural phenomena by performing ex- 

 periments for themselves in laboratories.' 

 Although not quite definite, this seems to imply 



