THE WEATHER S PHY NX. 625 
rely too exclusively on rrietely local appearances, which, at best, may prove de- 
ceptive. 
Perhaps of weather predictions that in regard to temperature is the safest, 
or at least most frequently desirable in a remote locality. 
Still, even for this there must be weather bulletins, and it is almost as neces- 
sary to see such bulletins, either in a daily paper or in a convenient place to 
study them, as it is to have eye-sight to get any ideas from a book. 
Weather charts are undoubtedly the best form in which these reports can be 
presented. Several skeleton charts have been invented. One by Mr. Isaac P. 
Noyes, of Washington. But he can get no newspaper proprietor to take hold of 
it and make it go; and though I tell him to advertise it and make its value appar- 
ent to the public, as a " long felt want," he has not yet made it available to the 
world. 
The bulletins issued by the Government at stations have the disadvantage 
that few care to stand up in a public place and study, for any length of time, 
the somewhat confused programme there presented to view. A studious man 
wants things comfortable — an easy chair, a quiet library, security from interrup- 
tion and especially an arrangement of stations geographically adjacent. 
Taking such a bulletin, or one as near it as a person can get hold of, if he 
wishes to find whether it will be warmer or colder during the next twenty-four 
hours, he regards attentively the point from which the wind is blowing at his own 
station, and following this direction, backward, notes how far the same wind- 
direction continues and, incidentally, the wind-velocity, and the difference in 
barometric pressure. In nine times out of ten the wind will bring the tempera- 
ture of the place from which, in a certain number of hours, the wind is blowing, 
at its reported velocity. But there is one exception. The temperature falls as 
we rise above the earth's surface at about the rate of one degree to every 300 
feet, or 20° to a mile. Warm air rises and cold air rushes in to fill the space 
left, and when air from a higher elevation comes to the surface of the earth it 
brings that lower temperature with it. Such change usually occurs after an area 
of low barometer passes. The cold northwest wind that generally follows does 
not, necessarily, come from a long distance. It may come from overhead. 
Guarding against this contingency, we will say : 
The laws governing temperature act more uniformly and are more easily 
applied than those relating to barometric changes. They may be formulated as 
follows : 
The temperature of a place, at any time, depends upon the actual amount 
of heat received from the sun, influenced by the prevalence of a warm wind (gen- 
erally) from the south or a cold wind (generally) from the north, or a situation 
protected from either of these influences. 
The first cause — actual heat received — is the effect mainly of latitude; the 
second is the result of areas of low barometer, producing if the track is north of 
a station, wind from the south ; and wind from the north if the track is south of 
the station. 
