Public Botanical and Horticultural Gardens. - That of Birmingham being only just commenced [Editors note: the garden was designed by The Conductor - J C Loudon], we can say little about it, farther than stating, that, we trust, when the objects of the garden and the plan that we have given shall be generally known, the garden will be liberally supported, confident as we are that it will afford much gratification, and be of essential use to the town and its neighbourhood. The Manchester garden is far advanced; and though we do not altogether approve of the plan, and certainly by no means of the manner in which it has been planted, yet we have not a doubt that it will contribute materially to the spread of improved varieties of culinary vegetables and fruits, and to the education of a superior description of gardeners. Our objection to the mode of planting is, that it produces a general sameness throughout the garden; whereas, according to our ideas, there should not be one square yard of a scientific garden, with the exception of the turf and the gravel, the same as another; nor should the same species of plant, with a few exceptions in favour of plants of culture, such as fruit trees, culinary vegetables, and florists' flowers, occur in two parts of the garden. In the Manchester garden, as in every other containing an arboretum, the trees which compose it must necessarily be spread over a considerable extent of surface. They form in this garden, as they ought to do, belts, strips, and clumps throughout the whole; and, to shelter and bring up these arboretum trees, a number of others have been introduced among them as nurses. Now, what we object to in these nurses is this, that they are composed of one common mixture throughout the garden. They ought, in our opinion, to have been composed, in all cases, of the same genus as the family to be nursed. For example, there are 30 or 40 different species of oak, one plant of each; these we would have sheltered with the common oak. In like manner, all the different species of the genus Pinus we would shelter with the common wild pine; the firs, with the spruce fir; robinias, with the common pseudacacia; genistas, with the common broom, and so on. But, in our opinion, shelter is much less wanted than is generally imagined; and, wherever it could be done without in this garden, we would surround the specimen trees with turf, and dig only a circle round the stem, of from 1 ft. to 3 ft. in diameter, according to the nature of the tree. Ultimately, almost every tree and shrub (we do not speak of under-shrubs) of the arboretum will stand on turf; and the sooner an approximation is made to this the better: it will add greatly to the variety and intricacy of the plantations in a picturesque point of view, and be much more convenient for botanical examination. With respect to flower-borders and rockwork, we would adopt precisely the same principle. In the rockwork, we would place every genus by itself in an irregular group; and, instead of having 20 or 30 plants of some showy or very suitable plant distributed all over the rockwork, thus giving it a general sameness of character, we would bring the whole 20 or 30 plants together in an irregular group; thus, where we had beauty in abundance, presenting it in masses. But when we come to publish our plan of the Birmingham garden, together with the plan of the Manchester one, which Mr. Mowbray has kindly promised us, we shall enter into further details. In the mean time, it is but justice to Mr. Mowbray to state that the present plan, which is almost entirely his own, is greatly superior to all the different plans which were sent in for competition; and also that he is open to reason, and, we believe, will adopt our principle of planting in future. We, also, are open to reason, and not wedded to any plan, but only to principles, to which we shall be most happy to publish every objection that can be urged. We were very much gratified by some details in the plan of the hot-houses, all of which have been executed by Mr. John Jones of Mount Street, Birmingham; who, from the great number of excellent structures, which we have seen since we left London, executed by him, we do believe to be decidedly the best hot-house builder in Britain. We were particularly gratified by Mr. Mowbray's arrangements of the back sheds, and the living-room and sleeping-rooms for the journeymen. Mr. Mowbray, having, when a journeyman, lived in the wretched stoke-holes of the Comte de Vandes's garden at Bayswater, and read there in the winter evenings by the light of a furnace-door, is not altogether ignorant of what is wanted in such cases, and of the difference between the services of a man rendered comfortable and of one treated worse than a dog or a pig. We were not less gratified at the manner in which Mr. Jones has heated the houses by hot water; though a number of the garden committee were at first very much against this mode of heating. Mr. Mowbray informed us that last winter the man could make up the fires for the night at five o'clock, without needing to look at them again till the following morning at eight or nine. The houses were always as hot as could be wished, and might have been kept at 100ï¾¦, if it had been thought necessary. A young gardener, from Mr. Mearns at Shobden Court, who had been accustomed, when there, to sit up half the night, during winter, to keep up the fires to the smoke-flues, was overcome with delight when he came here, and found how easy the task of foreman of the houses was likely to prove to him, as far as concerned the fires and nightwork. We are quite at a loss to conceive how Mr. Paxton can reconcile himself to smoke-flues, with evidence of this kind before him. We mention this, not so much for the sake of Mr. Paxton's hot-house productions, as for the sake of his men, and for the sake of other men in similar cases.