712 



SCIENCE. 



[N. S. Vol. III. No. 71. 



water supply contaminated with the discharge 

 of a person suffering from one of these diseases 

 have now been observed and recorded in suffi- 

 cient number, and with enough accuracy, to 

 have convinced both scientific men and the 

 public that this is the most common cause of 

 great outbreaks of these diseases, and that the 

 spread of the specific bacteria which produce 

 them is the means by which such impure waters 

 produce their destructive results. The work of 

 Professor Mason presents abundant evidence of 

 this in the form of statistics of different cities, 

 and of records of individual outbreaks, and 

 gives a fair summary of existing methods of 

 testing and of purifying water supplies. In the 

 chemical part of the book the writer gives his 

 own experience in water analysis, and the di- 

 rections are clear, concise and well up to date. 

 He confirms Dr. Smart's remarks as to the im- 

 portance of the rate of evolution of the so-called 

 albuminoid ammonia, in the distillation process, 

 but it is curious that no allusion is made to the 

 fact that the prolonged giving off of albuminoid 

 ammonia indicates, in many cases, the presence 

 of urea, and, therefore, of sewage, in the water. 



The chapter on the artificial purification of 

 water is a good summary for the general 

 reader, but it is not made as clear as it should 

 be that, in large sand filtration plants, no 

 single filter bed should exceed a certain size, 

 say one acre, and that the eflBuent from each 

 filter bed should be tested bacteriologically at 

 least once a week, and in many cases once a 

 day. In other words, a small bacteriological 

 laboratory and the services of a skilled bacteri- 

 ologist are essential features of such a system of 

 filtration. 



Among other epidemics of typhoid fever de- 

 scribed is the well known one at Lausen, in 

 which the infected water passed through the 

 base of a mountain, and such passage was 

 demonstrated by adding salt to the water. 

 Flour was also added, and did not pass 

 through, but it is doubtful whether this is. a sat- 

 isfactory proof that the water was really ^fil- 

 tered ' in its passage. 



Taking it altogether this is decidedly the 

 best book on water supplies that has yet been 

 produced for American readers and as such 

 it is cordially commended. 



SCIENTIFIC JOURNALS. 

 PSYCHE, MAY. 



The leading article by Prof. V. L. Kellogg 

 gives a general account of the Mallophaga, 

 with a key to the genera. W. S. Blatchley 

 continues his account of the winter Coleoptera 

 of Vigo Co,, 111., and Mr. A. P. Morse his notes 

 on N. E. Tryxalinse. J. W. Folsom examines 

 the types of Packard's Papirius texensis, and 

 finds two species among them, one a Papirius, 

 the other a new species of Smynthurus, which 

 he describes. H. G. Dyar describes the larva 

 of Cautethia grotei. T. D. A. Cockerell reviews 

 Dalla Torre's recent catalogue of bees, and F. 

 C. Bowditch gives some notes on the habits of 

 two beetles. Miscellaneous notes complete the 

 number. 



THE PSYCHOLOGICAL REVIEW. 



The articles in the May number are re- 

 searches from the psychological laboratories of 

 Chicago,IIarvard and Wisconsin. From Chicago, 

 Prof. Augell and Dr. Moore report on reaction- 

 time experiments in which the attention was 

 alternately concentrated on the attention and 

 on the movement, the stimulus being a sound 

 or a light, and the movement being made with 

 the hand, foot or lips. The reaction-times 

 were on the whole shorter when the alteration 

 was motor, but not to the extent nor with 

 the regularity claimed by the Leipzig experi- 

 menters, and the distinction tends to be obliter- 

 ated or reduced by practice. The authors dis- 

 cuss their results in their relation to attention 

 and habit. In a second research from Chicago, 

 Mr. L. G. Whitehead communicates experiments 

 on visual and aural memory which show that 

 of the thirteen observors tested, ten were able 

 to memorize more rapidly when the series was 

 seen and two when it was heard, while in one 

 case the result was doubtful. Matter mem- 

 orized aurally appeared to be retained slightly 

 better than that memorized visually. 



Dr. Edgar Pierce, now of the University of 

 Michigan, publishes experiments carried out in 

 the Harvard laboratory on the aesthetics of sim- 

 ple forms with special reference to eye move- 

 ments. He determined the preferences of dif- 

 ferent observers for figures in different positions, 



