Water being an essential application to the seed, as well as to the growing plant, the source from whence it comes is by no means immaterial. The best for the gardener's purpose is rain water, preserved in tanks sunk in the earth, and rendered tight either by puddling or bricks covered with Parker's cement. To keep these tanks replenished, gutters should run round the eaves of every structure in the garden, and communicate with them. Every hundred cubic inches of rain water, contains more than four cubic inches of air, of which more than half are carbonic acid gas, and the remainder nitrogen and oxygen in the proportion of sixty-two of the former to thirty-eight of the last named.

Liebig, from actual experiment on a large scale, states that both rain and snow contain ammonia; and its importance appears from the fact that if there be only one-fourth of a grain in each pint of water, the annual deposition from the atmosphere would be more than sufficient, on half an acre of ground, to give all the nitrogen contained in the vegetable albumen of 150 cwt. of beet root. Rain water also contains a peculiar substance, analogous to the extractive matter and gluten of plants, though differing from them chemically. To this substance, Dr. Daubeny has given the name of pyr-rhine. Traces of salts and oxides have also been found in rain water, but, compared with all other naturally produced, it is so pure, and so abounds with the gases beneficial to plants, that none other can equal it for their service.

That obtained from ponds or springs, invariably contains matters offensive or deleterious to plants. That known as hard water, containing an excess of salts of lime or magnesia, is invariably prejudicial, and pond water is scarcely less so. If it be stagnant, and loaded with vegetable extract, it is even worse than hard spring water; for it then contains carburetted hydrogen and other matters noxious to vegetables. These last named waters, if obliged to be employed to tender plants, should have a pint of the ammoniacal water of the gas works, mixed thoroughly with every sixty gallons, an hour or two before they are used.

Mr. Paxton justly observes that "watering outdoor crops is frequently recommended during continued dry weather; but it should be avoided as long as possible, as the benefit of artificial watering is but temporary, and it has the effect of exciting the roots, thereby rendering them more liable to suffer when the water has evaporated. When, in a case of emergency, it becomes necessary to water, it should be given morning and evening, more abundantly than is usually done, and never discontinued after its commencement, until a change in the weather renders it no longer necessary. Discrimination should be used in selecting proper objects for watering; for it is no uncommon occurrence to see small basins of soil formed round the stems of fruit trees, on walls and other permanent plants, into which several pans of water are poured daily during drought. This must be useless or nearly so, as the roots which would take up the water, for the benefit of the plants, will form a circle at a considerable distance from the stem.

Seed beds, or plants which can be regularly and thoroughly watered, as radishes, lettuce, and salading, will be much benefited, butartificial watering out of doors, in the manner it is usually applied, is of little service; and in the case of strawberries, and similar crops, mulching with straw, grass, or some such contrivance, which will prevent the rapid evaporation of moisture from the soil, is much preferable." - Gard. Chron.

Mr. S. Taylor, of Stoke Ferry, in the Gardeners' Magazine for 1S40, recommends the use of bottles with two small holes in the sides near the bottom, for watering plants. The bottles are buried to the neck, near the roots of the flower which requires watering, and after being filled and corked, the water is allowed gradually to exude through the holes. "This,"says that good horticulturist, Mr. W. P. Ayres, "though undoubtedly an ingenious method, is objectionable, because the roots of the plants are liable to be injured in plunging the bottles, and that it would require so many of them, where copious watering was necessary. A better plan is to take moderate sized flower-pots, and having placed an inch or two of rough gravel in the bottom of each, to place them round the plant to be watered, and fill with water, which as it percolates gradually through the gravel, will soak into the ground. For plants such as standard roses, rhododendrons, etc, closely turfed over on lawns, or for any thing in a sloping situation, this is a most excellent plan, as the pots filled with water may be placed at night, and removed the next morning, so as not to become an eyesore.

Watering plants in flower beds is at all times a difficult matter, because if the borders are sufficiently full of soil to give them a convex form, which they always ought to have, the water runs to the sides of the borders as fast as it is poured on. In such cases it will be found advisable to perforate the beds as thickly as possible, without injuring the roots, to the depth of six or eight inches, with a stick one inch in diameter, and by filling these 40 ten or a dozen times, the ground will become thoroughly soaked. With annuals, verbenas, and other grouping plants, I have found this a most excellent method. In connection with the watering of strawberries, a radical improvement is required; for although gardeners are prettly liberal with the limpid fluids over the heads of the plants, they are not good conservators of the quality of the fruit. It is true, by copious watering, both the size and quantity of the fruit is much increased; but it is equally true that if water is used over the plants after the fruit is half grown, the latter will be much deteriorated in quality.

We all know that strawberries in a wet season are never so high flavoured as they are in a dry one, and what is the reason ? Why, because there is a superabundance of aqueous matter in the fruit; and so it is with the plants copiously watered overhead in dry seasons. In truth, it may be laid down as a rule, if fine flavoured fruit be a desideratum, water ought never to come in contact with it after the saccharine or maturing assimilation commences. Hence in watering strawberries, let it be poured from the spout of the watering pot upon the soil, but on no account is it to touch the fruit; or, what will be better, fork the ground over between the plants, give it a good soaking, to at least the depth of a foot, and cover it two or three inches deep with clean straw. This will both prevent the evaporation of moisture, and the radiation of terrestrial heat; and as the straw, from its colour and non-conducting qualities, will reflect instead of absorbing the heat, the fruit, being subjected to increased temperature, will, in consequence, be improved in flavour.

If water is required after the straw is placed on the beds, let it be applied through pots, placed one foot apart, as recommended above for plants on a lawn." - Gard. Chron.

I agree with those who recommend "sunrise as the best time for the watering of exposed plants. Evaporation no doubt will then go on freely; but the atmosphere is beginning to get warmer, and the sun's rays to exert their counteracting influence. The darkened surface - that very condition which made the soil throw off its heat more readily during the night, causes it to imbibe the heat of the sun's rays by day with increased facility, so that you thus have the greatest amount of the fostering agencies of heat and moisture for the growth of plants. When evening again comes round, the surface moisture has been dried up, and its colour again rendered of a lighter shade ; there is consequently little diminution of temperature beyond surrounding objects, either from evaporation or radiation of heat." - Gard. Chron.

Although an excess of water applied to the roots of plants is injurious to them, yet all of them are benefited by a due supply of that liquid, and the supply has to be regulated by the amount of their daily transpiration. The gardener knows that this differs in every species, and during different seasons. For instance, in a dry hot day, a sunflower three feet and a half high transpired 111b. 4 oz., being seventeen times more than the human body; during a hot dry night, 3 oz.; during a dewy night there was no transpiration, and during a rainy night the plant absorbed 3 oz. Therefore, the gardener finds it best to apply water during dry weather early in the morning, just before the chief demand occurs, which is from six A. M., till two in the afternoon ; and during moist weather he refrains from the application entirely. Then again the gardener keeps his agaves and other fleshy-leaved plants in a dry stove, for they transpire but sparingly in proportion to their mass, and require watering but seldom, and then abundantly; for they take up, as in their native silicious habitats, a large supply, and retain it pertinaciously in defiance of the long-protracted droughts to which they are exposed.

In the same species I have always found varieties transpire abundantly and require a large supply of water in proportion to the extent of their transpiring surface. Thus the broad-leaved fuchsias and pelargoniums transpire from two to three times as much as those varieties which have smaller and less abundant foliage. Excessive moisture induces that over succulency, which is ever attended by weakness, unnatural growth, and early decay. Such plants more than any others are sufferers by sudden vicissitudes in the hygrometric state of the atmosphere, and are still more fatally visited, if exposed to low reductions of temperature."-Princ. of Gard.