454 THE POPULAR SCIENCE MONTHLY. 



We have thus obtained simultaneously the traces of the velocities 

 of translation of the artificial bird, and the durations of the depres- 

 sions of its wings, and we have obtained a series of determinations of 

 which the preceding figure (4) furnishes some examples : 



Experiment No. 1. The upward indentation in the line a shows the 

 duration of the depression of the wings. Taking that length on the 

 scale of time, we see that the downward movement of the wing lasted 

 less than -J- of a second. In that experiment there was no translation 

 of the bird. The line b does not show any indentation. 



Experiment No. 2. The duration of the depression of the wings 

 (line a) is already greater ; it exceeds one-half of a second. The 

 translation was then nearly three metres per second. We find this by 

 taking in the dividers the length on the line b of the 3 double inden- 

 tations of the tracer, which show that 3 times -^ of a metre, or 1.4 

 metre, have been traversed by the artificial bird. We carry this length 

 to the scale of time, and we find that it is contained about twice in a 

 second. We thus see at once that the duration of the downward mo- 

 tion of the wing increases with the velocity of translation of the arti- 

 ficial bird. 



Experiments Nos. 3-6. In the remaining experiments, proceed- 

 ing as we have already done, we find that the duration of the depres- 

 sion of the wing increases with the velocity of translation, and that 

 with a velocity of 5| metres the downward movement of the wing 

 lasts about one second. I have not been able to find the accurate re- 

 lation between the velocity of translation and the duration of the down- 

 ward motion of the wing. Experiments made in precisely the same 

 conditions sometimes present slight differences, which are due to the 

 fact that the slightest oscillation of the iron wire, which serves as a 

 support and guide for the artificial bird, slightly changes the durations 

 of the phenomena. From the first series of experiments, it would ap- 

 pear that the duration of the depression of the wing increases in pro- 

 portion to the velocity of its translation, at least within the limits of 

 the velocities with which I have experimented. 



THE RELATIONS OF WOMEN TO THE PROFESSIONS 



AND SKILLED LABOR. 



By ELY VAN DE WAEKEE, M.D. 



THERE are fields of labor in which women have been immemorially 

 active. In all matters relating to the cares of the house and chil- 

 dren among the civilized, and, among the barbarous and the lowest 

 strata of life in Europe and elsewhere, field-labor, the care of animals, 

 and the lighter manufactures, are the tasks imposed upon women. 



