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POPULAR SCIENCE MONTHLY. 



animals. They love to learn, and the imi- 

 tative instinct natural to them permits them 

 to execute all sorts of feats with agility. 

 They learn tricks more readily than dogs, 

 and, although not manifesting so hearty good 

 will toward the public, execute them with 

 marvelous agility and grace. At Hagen- 

 beck's establishment in Hamburg, where 

 two hundred monkeys enjoy complete liberty 

 of play in the great rotunda, they are given 

 multitudes of children's toys, balls, hoops, 

 wheelbarrows, joiner's benches, etc., and 

 learn to manage them all without any one 

 showing them how. In the center of the 

 rotunda is an immense grain hopper, from 

 which the seeds, corn, walnuts, chestnuts, 

 apple quarters, etc., run into a trough when 

 a wheel at the top is turned. The manage- 

 ment of this hopper did not have to be ex- 

 plained to our friends the monkeys. While 

 one of them turns the wheel, .the others, 

 sitting around the trough, enjoy the delica 

 cies as they come down, till the one at the 

 wheel, thinking his turn has come, stops, 

 gives the signal for some one to take his 

 place, and comes down to get his share. 

 What other animals are capable of so intel- 

 ligent an initiative ? 



Minute Earthquakes. Very delicate ex- 

 periments have been instituted by Prof. John 

 Milne to determine the stress inflicted upon 

 the earth's crust by small, even minute, dis- 

 turbances, whether local earthquakes on a 

 small scale, faint echoes of more violent dis- 

 tant disturbances, those arising from me- 

 teorological causes which are receiving spe- 

 cial attention or even those which are due 

 to the falling of rain and to dew. A shower 

 of rain or a deposit of dew represents a con 

 siderable load on the soil, which may per- 

 haps be regarded, in the first instance, as uni- 

 formly distributed, but which will probably, 

 because of inequalities in evaporation, not 

 remain so long. The ground on the east 

 side of a building will be more quickly dried 

 than that on the north ; the dew on the east 

 side will evaporate before that on the west 

 side, and so on. Thus there will be bending 

 stresses in the soil tending to tilt buildings 

 or piers for instruments that have not deep- 

 laid foundations. Tilts due to rainfall would 

 be irregular ; those arising from dew would 

 show a diurnal period. The inquiry is made 



whether these tilts are large enough to affect 

 astronomical observations. Diurnal oscilla- 

 tions of several sections of an arc have been 

 detected by seismographs in Japan, which 

 Prof. Milne attributes to the evaporation of 

 dew. At the observatory of the University 

 of Oxford a disposable weight, consisting 

 of a crowd of human beings, was utilized. 

 Formed into a solid square, they were marched 

 back and forth, to and from the observatory 

 wall. They were then spread out so that 

 they only touched by the finger tips; and 

 again so as to cover four times the space of 

 that formation. This was supposed to repre- 

 sent the evaporation effect. Seventy-six per- 

 sons were thus employed, and their march- 

 ing back and forth produced an appreciable 

 bending of the earth. As an aid to his re- 

 search, Prof. Milne has had a horizontal 

 pendulum set up in the Isle of Wight, in or- 

 der to obtain a continuous automatic record 

 of such disturbances as are there manifested. 



Improvement In Antitoxin e-Making. 



In a recent number of the Archives des Sci- 

 ences Biologiques issued by the Imperial In- 

 stitute of Experimental Medicine at St. Pe- 

 tersburg is an important announcement by 

 Dr. Smirnow, describing a new method of ob- 

 taining diphtheria antitoxine. Hitherto the 

 preparation of the antitoxine has not only 

 involved great expense, but also much time, 

 several months oftentimes. The new meth- 

 od announced by Dr. Smirnow institutes a 

 great saving in both time and expense, and 

 consists simply of electrolyzing a virulent 

 diphtheria broth culture, which is then found 

 to contain an antitoxine of great power and 

 efficacy. Dr. Smirnow states that a dog 

 weighing from eighteen to twenty pounds, 

 inoculated subcutaneously with 0*5 cubic 

 centimetre of a virulent diphtheria broth cul- 

 ture, usually dies in two or two and a half days. 

 If, however, even one day after inoculation, 

 treatment with the new serum is begun, from 

 three to five cubic centimetres of the latter 

 suffice to save the animal. 



Maxims for the Holiday. The first 

 requisite to the complete enjoyment of a 

 holiday, as laid down by the London Lancet, 

 is to have earned it. Only a true workman 

 thoroughly enjoys his season of rest, while 

 the idler, the trifler, the man of pleasure, 



