390 



SCIENCE. 



[Vol. IX., No. 220 



It will be readily recognized as a myth of wide dis- 

 persion. Perhaps the delicate fur and the grovelling 

 habits of the little animal account for it. 



3. Once the mole had eyes like other animals, but 

 no tail. He met a creature which ridiculed him for 

 his poverty in this latter respect. The derision 

 preyed on his mind, and, when he met a being who 

 could help him, he petitioned for aid. He was told 

 that he must give up his eyesight ' So he sold his 

 eyes for his tail.' \V. H. Babcock. 



Washington, D.C., April 16. 



Some hardy buds. 



While in the country two weeks ago, my wife cut 

 some branches from a pear and a cherry tree, and 

 also from a lilac-bush, and brought them to the city. 

 At that time the buds looked as they had all winter ; 

 in fact, we thought the pear cutting was dead. In 

 a few days the buds commenced to open, and today 

 the cherry-blossoms are out, as they would be on the 

 tree, the blossoms of the pear are just opening, and 

 those of the lilac are bpginning to show. The water 

 in which they were placed has been changed daily, 

 and the cuttings kept in the sun as much as possible. 

 It has occurred to us that such cuttings might be 

 placed in rooms where there are invalids, both in 

 homes and in hospitals, and give the sick a taste of 

 the country which they could otherwise not get. It 

 is no less an object of interest and instruction to the 

 well : the daily, and I might say hourly, changes in 

 the buds as they unfold are fascinating to watch, 'and 

 even those whose lives have been spent in the coun- 

 try have never seen the gradual desrelopment of the 

 blossoms as they can thus see them on the severed 

 branches. J. H, R. 



Brooklyn, April 8. 



On tiptoe. 



While feeling honored that the attention of so 

 eminent a physicist as Professor LeConte should be at- 

 tracted to the question which has been recently dis- 

 cussed in Science under this heading, it still seems 

 to me, as it did when I called the attention of Pro- 

 fessor Van Dyek to the matter, that the lever is of 

 the first order. 



Professor LeConte quietly assumes that the point 

 C (adopting his figure. Science, ix. p. 341) is the ful- 



crum, but just there is the question. Suppose a per- 

 son sitting down to put his toe against some object, 

 and, by the same muscular action which raises the 

 body on tiptoe, to push the object away. Here the 

 case is evidently a lever of the first class, the ful- 



crum being the ankle-joint (i?), and the weight the 

 point of the toe's pressure ((7). 



Now suppose, that, in precisely the same way, he 

 presses his toe against some firmer object, as a wall, 

 and, instead of ptishing it, pushes himself away. 



I fail to see how it is other than an unnecessary 

 complication, at least from a physiological stand- 

 point, to suppose the fulcrum and weight to change 

 places, so as to make the lever one of the second 

 class. Further, in cases where the resiilt is partially 

 a movement of the object, and partially of the per- 

 son's body, — as in rising on tiptoe upon a yielding 

 object, — the complication of the solution upon the 

 hypothesis that the lever is of the second class is 

 further increased ; whereas in every case, since the 

 foot still turns upon the ankle-joint B, by regarding 

 it as a fulcrum and the lever as of the first class, 

 the conclusion reached by Professor LeConte, that 

 P -.W :: CB : AB, becomes an evident application of 

 the general law of mechanics. Edwin J. Pond. 



Austin, Tex., April 12. 



Winds in Denver. 



H. A. Howe, in Science, No. 216, asks " why winds 

 blow at Denver from the north during the day, and 

 from the south at night." 



It is for these reasons : Denver is in a canon run- 

 ning north (the mountains on the west, a slight ele- 

 vation on the east, and a ' divide ' on the south), 

 through which flows Cherry Creek. Now, winds 

 invariably blow up canons during the day, and down 

 them at night. This brings the question to, " Why 

 do winds blow up canons during the day, and down 

 at night ? " which I take to be the intended interrog- 

 atory. During the day, the sun heats the air, which, 

 becoming light, rushes up the canons, while at night 

 the air becomes cool and seeks lower altitudes. Of 

 course, the disturbed equilibrium increases the wind's 

 velocity. I think I have crudely answered the 

 question. P. F. Wtman. 



Silver Reef, Utah, April 7. 



Geographical centre of the United States. 



If an area or district of country is mapped on a 

 projection of small areal distortion, the geograph- 

 ical centre of the area may be defined to be the 

 centre of gravity of the figure. 



The problem to determine the centre, would, 

 under this definition, resolve itself into the question 

 of determining the centre of gravity of a plane figure 

 of irregular outline. Of the various ways in which 

 the centre of such an area may be found, the me- 

 chanical ones are perhaps of easiest application, 

 and, on the whole, yield the most satisfactory re- 

 sults. 



One^method consists in tracing the outline of the 

 area whose centre is to be determined, on stiff 

 cardboard, then cutting out the figure along the 

 boundary so traced, and balancing the resulting 

 cardboard on a point ; which point so found is the 

 point sought. 



Another way consists in cutting out the map, as 

 before, along the boundary-line, and then suspend- 

 ing it behind a plumb-line, so that map and plumb- 

 line hang from the same support : the projection of 

 the plumb-line on the map is a line which passes 

 through the centre of gravity of the area. By sus- 

 pending the map successively from several differ- 



