3 i6 THE POPULAR SCIENCE MONTHLY. 



principle that we must know much more about a climate than 

 what the thermometer can tell us before we know very much 

 about it. I kept a record of the temperature in Martinique, one 

 of the Windward Islands lying in 14 north latitude, and it never 

 went above 86 F., nor so high but two or three times during a 

 residence of three seasons, and once so late as the 1st of July. 

 But no sensible person would dare to expose himself to the mid- 

 day sun with the same impunity that he could in this latitude 

 and a corresponding temperature. The ever-present humidity, 

 bordering on saturation, in the tropics is an important modifying 

 element to be taken into account. 



Again, temperature may depend on latitude or on altitude ; but 

 it is not a matter of small moment which the cause may be. Sixty 

 degrees of heat at the level of the sea and on the seashore are very 

 unlike in physiological effect to 60 in the dry and rarefied air of 

 an elevated inland situation. There is no doubt that considerable 

 moisture in the air favors the growth of minute organisms, and 

 decomposition of matter takes place rapidly under the influence 

 of heat and moisture. On the other hand, a dry air retards de- 

 composition, and, if sufficiently dry, prevents it entirely, no 

 matter how hot it may be. The Sacramento Valley is very hot in 

 the summer, but it is also dry, so that friends of mine would kill 

 a beef and elevate the carcass by means of rope and pulley to the 

 top of a tall pole, let it down from time to time to cut from it, and 

 it would keep perfectly sweet until it was all eaten up. A good 

 illustration of conditions retarding or favoring the growth of 

 minute organisms may be seen during the orange harvest in por- 

 tions of California. The altitude of Redlands, California, aver- 

 ages about fifteen hundred feet above sea level. Fogs seldom 

 reach there, the sun shines clear more than three hundred days 

 of the year, and there is not a speck of mildew on any fruit. But 

 go forty miles nearer the sea and seven or eight hundred feet 

 down nearer the sea level, and at every station you will see many 

 people washing oranges. More fogs, denser air, less sunshine, 

 more humidity favor fungous growths. On the high table lands 

 of the central portions of the continent, at an altitude of six or 

 eight thousand feet, as in Wyoming, where a friend lives, milk 

 does not " sour " or change under a week or ten days, and the 

 carcasses of dead cattle, of which there are many, give no offen- 

 sive stench, but slowly dry up and waste away, showing that 

 comparatively few organic germs exist there, and that the con- 

 ditions for their rapid propagation are unfavorable. From the 

 facts just stated and they are representative facts it would be 

 too hasty to conclude that the higher and drier locality is es- 

 sentially more healthy than the lower and moister locality, even 

 for consumptives, until we have mastered and estimated the 



