ED. Western Horticulturist: Ordinary thermometers indicate the temperature only at the instant of observation. Unless observed constantly the duration of any degree of temperature is not shown. Practically, duration is a very important matter in determining influences of temperature. Suppose that a hot-house is to be managed, or nursery stock to be moved. The thermometer may indicate 10° on the morning of any day about the middle of October, and endure at that for only three or four hours. Less damage would be done to living plants than when, two weeks later, the mercury shows 15° or 20°, but remains at that for two days. In the latter case the earth and plants become cooled so as to be constantly freezing; in the former case the latent heat would not all be taken from the ground to permit freezing so soon. The earth in the first instance would not freeze so as to injure potatoes, flower-roots, etc., when in the latter ease they would be entirely destroyed.

Extremes, not means, are the practical features of climate. The fact that the average temperature of May is 50° is not so important a fact to horticulturists as that the cold of May is 25° often as late as the 25th of the month. The probability of excessive heat or untimoly frosts must modify the action of gardeners, florists and farmers in planting, and nurserymen in the moving of articles liable to injury by extremes of temperature.

In view of these and kindred facts we would suggest to scientists the desirability of a self-registering thermometer, one that will show the temperature at any and all times, in all its fluctuations, variations and extremes. Is not such an instrument practical?

Ithaca, Wis. A. L. Hatch.