May 22, 1896.] 



SCIENCE. 



765 



•wMch was quite ronnd, except for two pro- 

 jecting stones. Here perfectly packed in 

 with loose earth were twenty-five eggs, 

 while again in a hole one and one-half 

 inches deep, at the bottom of the tunnel, 

 were fifteen more. Since the embryos of 

 one of these sets were at a considerably 

 more advanced stage, this female must 

 have taken advantage of the excavation of 

 another. At the time of ovulation the em- 

 bryo, while at an advanced stage, is still not 

 ready to hatch by probably some days or 

 even weeks. This stage will be considered 

 in detail in a later paper on the embryology 

 of Phrynosoma. 



Authors give the period of gestation 

 as high as one hundred days in females 

 kept ia confinement, but while I have not 

 complete data from coition to ovulation I 

 believe that under natural conditions the 

 time of carrying the eggs is much shorter. 

 A female which had laid eggs in captivity 

 in August, 1864, became very restless after 

 the eggs were taken away. She tried con- 

 stantly for two or three days to get out of 

 the vivarium at the place where the wire 

 screen had been raised to remove the eggs. 

 Lockwood gives an instance of this ma- 

 ternal anxiety where a female attempts to 

 distract the attention of an observer from 

 her young. 



LORD KELVIN ON THE 3IETBIC SYSTE3L 

 The chief objection urged in the recent de- 

 bates in Congress against the adoption of the 

 metric system m. the United States was the 

 fact that Great Britain, with whom our 

 commerce is the largest, does not use the 

 system. It seems, however, certain that 

 the adoption of the system by both nations 

 is only a matter of time, and as the question 

 is now being considered, both by the British 

 Parliament and our Congress, it would be 

 highly desireable if an International Com- 

 mission could be arranged so that unity of 

 action could be secured by the two nations. 



The London Times, whose influence has 

 been said to be as great as that of Parlia- 

 ment, has recently given much space to dis- 

 cussion of the metric system. Of the large 

 number of letters addressed to the editor 

 ' we quote the following from Lord Kelvin 

 as of special interest : 



" In your very interesting leading article 

 on the metric system in The Times of yes- 

 terday you treat, in what seems to me a 

 thoroughly clear and fair manner, the ques- 

 tion at issue in respect to the demand for 

 legislation on the subject. 



"While not ignoring the preference oi 

 merchants and manufacturers and scientific 

 men for the metric system, you rightly give 

 prominence to consideration for the conve- 

 nience of the poorer classes, ' who have no 

 great power to make their voices heard — 

 at least in such discussions as these.' If it 

 were true that the adoption of the metric 

 system would be hurtful, or even seriously 

 inconvenient, to them, that would be a 

 strong reason against its being adopted in 

 England. But in this respect we have, 

 happily, a very large experience, and I be- 

 lieve it is quite certain that among the Ger- 

 mans, Italians, Portuguese, and other Eu- 

 ropean peoples who have had the practical 

 wisdom to follow the French in the metric 

 system, all classes are thoroughly contented 

 with it, and find it much more convenient 

 for every-day use than the systems which 

 they abandoned in adopting it. 



" You rightly brush aside the duodecimal 

 system as ' an ingenious mathematical ex- 

 ercise, but one whose figures must be read 

 back into a decimal system before they can 

 convey any meaning. ' It seems to me, how- 

 ever, that you are quite right in maintain- 

 ing that in ordinary every-day reckonings 

 the shopkeeper and his customers must 

 have halves and quarters ; but I cannot go 

 so far with you as to say ' halves, quarters 

 and thirds.' Was any poor child ever sent 

 to buy a third of a pound of tea ? Did any 



