Many house plants are destroyed by too much heat, which increases the dryness, and both these causes together are more than they can endure. A cool room, never as low as freezing, is best. From 60 to 55 degrees is much better than 65 or 70, the ordinary temperature of living rooms.

Syringing the foliage with tepid water, to wash off whatever dust accumulates, is of use; and the admission of fresh air, when there is no danger of chilling or freezing the foliage, should not be neglected.

## Temperature #1

Mr. O. C. Jones asks, on whose make of thermometer he is to place reliance, and if there be any standard one to test the accuracy of instruments bought? "O. C. J." may test his own very simply. There are two standard points on the scale of a thermometer, viz: the boiling and freezing points; and a third very nearly so, the zero. If " O. C. J." will insert his instrument in boiling water (the barometer being at 30 inches), the mercury ought to stand exactly at 212 deg. If he then insert it in melting snow or ice, it ought to stand exactly at 32 deg. Then, providing the tube be accurately made, and the scale properly graduated, all the intermediate points will be accurate; by continuing the same above 212, and below 32 deg., all the rest would be, also. The scale-bore of tube between 32 and 212 deg. may be verified by mixing equal or proportionate quantities of water of known temperature together, when the inserted thermometer ought to indicate a proportionate temperature on the scale, if the bore of the tube be accurate, which is perhaps never the case, though sufficiently so for all practical purposes. To find the zero-point, equal quantities of snow or pounded ice and common salt, mixed together, produce it very nearly.

In speaking of the accuracy of intermediate, etc, points between boiling and freezing, I have, of course, not taken into account the small error occasioned by the. ratio of expansion of glass tube and scale. W. G.

## Temperature #2

Notwithstanding the Camellia is a native of China, it will thrive best in the green-house - temperature, 45 to 50 degrees Fahr. If placed in the hot-house, in order to get the flowers earlier, they should not be crowded together with other plants, but placed by themselves in the coolest part of the house, where they can have plenty of air and light.

Any sudden change of temperature should be avoided as much as possible, as the Camellia is liable to drop its flower buds when this takes place. During winter, when the weather is mild and warm, do not neglect to give plenty of fresh air. A great deal of care must be taken not to give bottom sir, unless the weather is very mild; in fact, in a well-arranged green-house, sufficient air can always be given by lowering the top lights. Towards spring, when the weather commences getting warmer, the Camellias should gradually be hardened off until it is time to move them outdoors. The best place to stand them is against a northern wall, or on the north side of a building, where they will be sheltered from the direct rays of the mid-day sun, which is very apt to burn the young and tender shoots. Avoid placing your plants under trees; if no better place can be found, a temporary shed should be erected.