March 24, 1905.] 



SCIENCE. 



473 



THE METRIC FALLACY. 



To THE Editor of Science: Evidently Mr. 

 Samuel S. Dale, in the issue of Science of 

 March 3, 1905, under the above title, failed to 

 recognize his own mathematical proof of the 

 amount of saving in time that might accrue 

 in school vpith the use of the decimal system. 



His error probably arose through the use 

 of an artificial week by the board of educa- 

 tion merely for their own convenience in as- 

 signing the proportion of time in school for 

 each study. The time a child actually spends 

 in school is a small part of the year and it 

 would be a confusion of units to compare this 

 schedule week with a regular week because the 

 same word is used. 



The only way a comparison can rightly be 

 made is to take Mr. Dale's statement of what 

 the schedule week is in years — that is, for 

 elementary mathematics thirty-four and one 

 eighth schedule weeks require eight years' 

 work. On this basis 6.825 schedule weeks will 

 require one and three fifth years' work in 

 mathemati&s. 



It is, however, not necessary to introduce 

 this schedule week. The pupil actually spends 

 eight years, according to Mr. Dale, on the 

 text-books mentioned. As arithmetic during 

 all this time is a major study, it is taught to 

 the full capacity of the average child. Now 

 if twenty per cent, of this time, as is allowed 

 by Mr. Dale, is spent on tables of weights and 

 measures, evidently these will require all the 

 time available for mathematics during 1.6 

 years. 



It is probable that a child could easily learn 

 the decimal system in less than half the time 

 it takes to learn both the decimal system and 

 the several other unconnected tables. Ac- 

 cepting Mr. Dale's own figures, it seems, there- 

 fore, reasonable to suppose that the average 

 pupil would save from two thirds of a year 

 to one year of the one and three fifth years, 

 now required, and would be about a year ahead 

 in mathematics at the end of the eight years 

 if he had only the decimal system to learn. 



I do not desire to enter upon any discussion 

 as to the merits of the metric system, but 

 simply to point out the mathematical error 

 in Mr. Dale's reasoning and to show that if 



his argument was worth anytliing at all, it 

 really proved the very statement he was trying 

 to refute. 



Henry B. Hedrick. 

 U. S. Naval Observatory, 

 Washington, D. C, 

 March 9, 190.5. 



A request for material. 



I have been at work for some time upon the 

 problem of double monsters among animals 

 and would be grateful for any material com- 

 ing under this head. I wish instances of 

 genuine double monsters, i. e., those involving 

 the doubling of some axial part of any verte- 

 brate, embryonic or adult (naturally, not too 

 large specimens), and am just now especially 

 desirous of cases among birds. As this is the 

 time of year at which embryological labora- 

 tories run their incubators, it seems likely 

 that several such instances will be found by 

 those not especially interested in the subject 

 and who do not care to investigate them. If 

 any such material appears superfluous I will 

 try to make good use of it. 



Harris Hawthorne Wilder. 



Smith College, 

 Northampton, IMass. 



SPECIAL ARTICLES. 

 elliptical human erythrocytes, (a supple- 

 mentary statement.) 

 On March 18, 1904, I published in Science 

 a note describing an unusual variation in 

 the shape of human erythrocytes. As was 

 stated in that article, the blood of a student 

 at the Ohio State University contained ellip- 

 tical red corpuscles, whose average length was 

 10.3 microns and whose average width was 4.1 

 microns. About 90 per cent, were thus de- 

 formed. The observation attracted consider- 

 able attention. Professor Austin Flint being 

 one among several who wrote to me for a 

 specimen of the blood. There resulted some 

 correspondence between Professor Flint and 

 myself, and in a letter to him I remarked that 

 some time after my observations had been 

 made the young man having these elliptical 

 corpuscles had died. Since the claim had 

 been made that the young man (a mulatto) 



