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THE POPULAR SCIENCE MONTHLY 



creases or diminishes in weight. Thus, if a 

 man or a woman weighing one hundred and 

 fifty pounds has a brain weighing three 

 pounds the proportion of brain-weight to 

 body-weight is as 1 : 50. But, suppose the 

 person loses fifteen pounds in weight, then 

 the proportion becomes 1 : 45, whereas if 

 there should be a gain of a like amount the 

 proportion would change to 1 : 55. In the 

 first instance, if relative weight has anything 

 to do with intelligence the mental power 

 would be increased, while in the other case 

 it would be diminished. Of course, no such 

 change takes place. 



Many years ago I made several thousand 

 observations in regard to the weight and 

 other qualities of the brains of various spe- 

 cies of animals belonging to the classes of 

 reptiles, fish, birds, and mammals. In these 

 investigations I went over to a great extent 

 the ground previously traversed by Leuret, 

 and in some respects made new observa- 

 tions. I found among other interesting facts 

 that the brain of the canary-bird, reared in 

 the United States, was in weight as com- 

 pared to the body as 1 : 105, and in the 

 Arctic sparrow as 1:11. These little ani- 

 mals have the largest brains relative to the 

 body of any others yet examined. To pre- 

 tend that they are superior in intelligence 

 to man, in whom the weight of the brain 

 relative to that of the body averages 1 : 36 - 50, 

 is, of course, ridiculous. Yet that is the 

 conclusion to which Miss Gardener, and pre- 

 sumably the "twenty leading brain-anato- 

 mists," etc., would have us come. 



Broca declares that the difference in 

 weight between the brain of woman and 

 that of man is not due alone to the smaller 

 size of her body, but to the additional fact 

 that woman is in the mean, when compared 

 to man, a little less intelligent; a fact, he 

 says, which should not be exaggerated, but 

 which is nevertheless real. This is going 

 somewhat farther than I have ever gone, 

 but what Broca says in a matter of anthro- 

 pology is worthy of serious attention. 



When Miss Gardener says that I make 

 relative difference " count for a great deal " 

 when existing between two men, she passes 

 the limits of correctness. I have never said 

 anything of the kind. 



One more point, and I have done. I 

 stated, in the paper on " Brain-Forcing in 

 Childhood," that the human head does not 

 grow after the seventh year, and Miss Gar- 

 dener, with the assistance of the " foremost 

 brain-anatomist of New York," is quite fa- 

 cetious over the assertion. Instead of head 

 I should have said brain, and then the 

 point involved would have been more cor- 

 rectly stated ; for the scalp, muscles, fasciae, 

 etc., of the head have nothing to do with 

 the issue which concerns the mind only as 

 derived from the brain. In regard to the 

 growth of the brain in size and weight, there 



i* abundant authority for the statement that 

 it ceases to advance at or about the seventh 

 year. Soemmering states that the maximum 

 is attained at three years. The brothers 

 Wenzel, at between six and seven years ; 

 and Tiedemann, at between seven and eight 

 years. Other observers have arrived at 

 different results, but there is room for a 

 difference of opinion on the subject, and 

 Miss Gardener should have been aware of 

 the fact when she dismissed the statement 

 as though it were entirely unauthorized. 



That the brain ceases to grow at a com- 

 paratively early age is abundantly estab- 

 lished by the observations of several com- 

 petent brain-anatomists. Thus, Dr. Boyd, 

 who based his conclusions on the examina- 

 tion of over two thousand brains, found the 

 average weight to be, at the age of from ten 

 to twenty, 485 ounces the maximum weight 

 for all ages, and four ounces heavier than 

 in persons whose ages ranged from twenty 

 to thirty. 



Broca, quoting from Wagner's tables, 

 gives the mean weight in persons of from 

 ten to twenty years as 51*7 ounces heavier 

 by 4"4 ounces than in persons from twenty 

 to forty years of age. 



The average weight of the brain in forty- 

 seven persons of English, Scotch, and Ger- 

 man nationality, as given by Thurnam in 

 one of his tables, is 49*6 ounces in those 

 whose ages range from ten to twenty years 

 a weight considerably in excess of that 

 shown for any other period of life. 



The general truth of the assertion made 

 in my paper on "Brain-Forcing in Child- 

 hood," that " the brain of a child is larger 

 in proportion to its body than that of the 

 adult" is, therefore, not only established, 

 but the additional fact inferentially stated, 

 that the brain is absolutely larger in child- 

 hood than in adults, is shown to be cor- 

 rect. 



And now I must bring this communica- 

 tion to a close, feeling that I have given 

 more attention to Miss Gardener than she 

 and the "twenty leading brain-anatomists, 

 microscopists, and physicians of New York " 

 deserve, and advising them that before they 

 again rush into print they make themselves 

 to some extent acquainted with the element- 

 ary truths of the science of anthropology. 

 William A. Hammond. 



THE EXPLOSION AT BRIGHTON, ILLINOIS. 



Editor Popular Science Monthly : 



Sir: The letter of Mr. A. 0. Fay, pub- 

 lished in No. 182, seems to call for a few 

 words in reply, for Mr. Fay appears to have 

 mistaken the purpose of the article to which 

 he refers. In the first place, the entire aim 

 of my article in No. 180 was to present the 

 phenomena connected with the explosion of 

 August 29, 1886, and not, as Mr. Fay seems 



