248 



THE POPULAR SCIENCE MONTHLY. 



Borelly, studying the stability and displace- 

 ment of fish, traced the plan of a diving- 

 ship constructed upon the same principle as 

 the formidable monitors which made their 

 appearance in the recent American war. 



"Aerial locomotion has always excited 

 the strongest curiosity among mankind. 

 How frequently has the question been raised, 

 whether man must always continue to envy 

 the bird and the insect their wings ; whether 

 he, too, may not one day travel through 

 the air, as he now sails across the ocean ! 

 Authorities in science have declared at dif- 

 ferent periods, as the result of lengthy cal- 

 culations, that this is a chimerical dream ; 

 but how many inventions have we seen 

 realized which have also been pronounced 

 impossible ! The truth is, that all interven- 

 tion by mathematics is premature, so long 

 as the study of Nature and experiment have 

 not furnished the precise data which alone 

 can serve as a sound starting-point for cal- 

 culations of this kind." 



The Maintenance of Health. By J. Mil- 

 ner Fothergill, M. D. London : Smith, 

 Elder & Co. New York: G. P. Put- 

 nam's Sons. 399 pp. 8vo. Price, $5.00. 



This is a useful work on hygiene, and, as 

 all intelligent hygienic action must be based 

 upon some knowledge of the human subject, 

 it opens with a description, in outline, of the 

 composition of the body, of its various or- 

 gans, the functions they perform, and the 

 relations of food, exercise, and sleep. Then 

 follows a consideration, in the natural order, 

 of youth, maturity, and old age, with the 

 dangers incident to each, and the precau- 

 tions necessary. 



In treating of the first stage, allusion is 

 made to a danger little known and less 

 heeded by people in general : this is, the 

 effect upon children of violent outbursts of 

 anger in parents and nurses. The young 

 wife, by yielding to anger under the trials 

 of her newly-assumed position, may doom 

 her unborn babe to an imbecile existence. 

 " The majority of imbeciles are first-born 

 children, and their pitiful condition is the 

 consequence of the mental perturbations 

 during the term of pregDancy." Again : 

 " In sucklings, too, mental disturbance in 

 the mother or wet-nurse will commonly 

 produce indigestion and diarrhoea in the 



baby." Nor does the danger end with in- 

 fancy. Nearly every one has observed the 

 deplorable influence which capricious pa- 

 ternal anger exercises upon children, some 

 being made gloomy and morose thereby, 

 others stubborn and revengeful. In con- 

 nection with children advanced beyond the 

 period of infancy, the author deplores the 

 aversion, which they at the present day dis- 

 play, to eating fat, and recommends that 

 parents should persistently endeavor to 

 counteract it. He says : " Fat is most 

 necessary to the proper growth of tissues, 

 and, such being the case, is still more ne- 

 cessary to children." Without it, children 

 grow up lean and spare. 



The consideration of the causes of dis- 

 eases in maturity is worthy of special at- 

 tention. One of the most subtile of these 

 causes, because little thought of, is the de- 

 cay of the teeth. This is said to be on the 

 increase, and is mainly attributed to ex- 

 cessive consumption of sugar, and the use 

 of dentifrices. " Many dentifrices contain 

 an acid which, by constantly eating away 

 a thin surface of the enamel, keeps the 

 teeth brilliantly white, but in time leads to 

 their utter destruction." 



Certain silly young ladies, who resort to 

 the drinking of vinegar or the eating of 

 raw rice, to avoid growing fat and florid, 

 will be edified to leam that the amount of 

 vinegar which will make them thin will de- 

 stroy their digestive powers, and that a 

 similar quantity of rice will produce habit- 

 ual constipation, and prevent the assimila- 

 tion of food. 



In advanced life, many persons suffer 

 much from inability to sleep. Moderate 

 exercise during the day, and, at night, beds 

 warmed before retiring, are recommended 

 as the best remedies. In obstinate cases, a 

 little alcoholic stimulant, mixed with warm 

 water, may be taken to advantage just after 

 entering bed. An important chapter is de- 

 voted to food and clothes, and another to 

 stimulants and tobacco. The recent classi- 

 fication of alcohol as a food is adopted, and 

 its use in small quantities considered harm- 

 less ; in certain cases beneficial. Tobacco 

 is also considered harmless in moderate 

 quantities. 



The chapter on mental strain, over- 

 work, and tension, deserves a careful pe- 



