656 



POPULAR SCIENCE MONTHLY. 



Wind, Maximum Velocity per Hour 

 10 20 30 40 50 60 



Murders 



Normal Velocity 



FIG. 2. 



and thirty miles, and so on, as indicated by the curve. Now, it can 

 readily be seen that this normal curve may also be considered the 

 expectancy curve if the wind has no effect. That is, if forty-eight 

 per cent of the days of the year show a maximum velocity of the 



wind, between ten and 

 twenty miles an hour, 

 the law of probability 

 would give us the same 

 per cent of the crime for 

 the year on such days if 

 this meteorological con- 

 dition were not effective. 

 What we do find, 

 however, is indicated by 

 the other curves, and 

 any increase of crime 

 over expectancy may in 

 this case be ascribed to 

 the wind. We notice 

 that for slight velocities (one to twenty miles an hour) the crime 

 curves are below that of expectancy, but we can see that if the 

 sum of all the per cents for any one curve is one hundred, and 

 one is forced above the other at any part, there must be a cor- 

 responding deficiency at some other part. So we may, perhaps, 

 with justice suppose that these mild velocities do not exert a 

 positively quieting effect emotionally, but simply a less stimulat- 

 ing effect than the higher ones. For velocities of between twenty 

 and thirty miles a marked effect is noticeable, and under those con- 

 ditions the proportion of suicides to that expected is 37 : 29; ve- 

 locities of from thirty to forty miles, 14 : 11; of forty to fifty 

 miles, 7:2; of fifty to sixty miles, 0.4 : 2.6; of fifty to sixty miles, 

 0.2 : 2. The curve for murders shows the increase to be slightly less 

 than for suicides, but the same general relation is preserved through- 

 out. The value of such curves is, of course, somewhat propor- 

 tional to the number of observations made and recorded, and we 

 must confess that two hundred and sixty (suicides) and one hundred 

 and eighty (murders) is a hardly sufficient number from which to 

 deduce a definite law, but we can hardly doubt, even considering 

 this somewhat limited number, that the wind is, in our problem, a 

 factor of no mean importance. 



TEMPERATURE. Fig. 3 is intended to show, in a similar man- 

 ner, the relation between expectancy curves, based upon conditions 

 of temperature, and the actual occurrence of the crimes in ques- 

 tion. With this class of data, as well as that for the barometric 



