The London Crystal-Palace, of 1851, designed by the then only Mr., afterwards Sir Joseph Pax-ton, the gardener to the Duke of Devonshire, was a clever structure, meeting the requirements imposed by the government on the architects better than any other plan proposed, and as unique as it was in its conception, grand in its dimensions, but imposing only on vulgar minds or coarse and uncultivated tastes, as quantity and size always do, it never was a beauty nor ever claimed to be by its own originator. It was at the beginning intended to serve but a temporary purpose, and the permission for its erection was granted upon the special condition, that it should be removed immediately alter the World's fair was over. Its re-erection for permanency was an after thought:; but the idea that it might serve as a plant-house never entered the mind of Paxton. He knew too much for that, and what he might have done in this direction, if afforded an opportunity, may be surmised after a careful and intelligent, study of the Conservatory at Chatsworth. The mistaken adoption of the style and the leading feature's of the Crystal Palace for horticultural structures, only proved a gross ignorance of the fundamental and indispensable requirements of contrivances for the maintenance and the proper display of plants.

To intrust the construction of them, if not carle blanche to engineers, at any rate with too much unwarranted faith in their superior genius and skill, is a great mistake. We ought to remember that engineers arc teehnicists, more or less scientific mechanics, and as a class have never shown much of an artistic turn of mind, nor anything like infallibility. When in the construction of our parks and conservatories, they are invited to furnish just as much and as little of their peculiar skill and ingenuity as is wanted or indispensable, they may prove very useful; but to make them the directing minds and final authorities in matters of science and art, for which they never had sufficient, time nor opportunities to qualify themselves, is a mistake which is sure to bring about such results as are already visible in but too many -places, and the repetition of which ought to be discontinued.

Horticulturists and landscape gardeners may easily add to their stock of knowledge what little is required of engineering, to get along without them; and before engineers can undertake to supersede the professional gardeners, they have to be initiated in mysteries beyond the power of screws and levers.

That monstrous bubble of glass in Ivcw-garden (constructed by a man whose legitimate business was to build railroad depots, and who knew well enough how, with iron and glass, to arch over wide spaces for the accommodation of several locomotives abreast), is, as a plant-house, about as suitable and useful for information as a racehorse is in its line, and Mr. Jeffreys in one of his critics on the "Horticulturist" calls it "a costly royal toy," adding that it is "a luxury of which I cannot well see the utility in so much expense." Well, would it be English if it were not costly? Only think of it - sixty thousand pounds sterling, to "dome" over only half an acre of ground, for the exhibition of more iron, tubs and pottery, than foliage and flowers, serving more to satisfy the vulgar curiosity of the London sight seers, than the scientific thirsts of students. For, what it is smaller in size and inferior in efficiency than the Chatsworth conservatory, covering an area of more than an acre, it makes up in useless, costliness and ostentation, like some people's books, of which the bindings cost more than the books themselves are worth.

The celebrated Palm-gardens, at Frankfort on the Main, originally built for the Duke of Nassau on his place at Biborich were, after his media; tisation, acquired by a society and removed to Frankfort, They have since been considerably increased in extent, and a richer collection of tropical and sub-tropical plants in large and fine specimens could not well be found in any other establishment. In this enterprise the society has expended up to this day the snug sum of about half a million of florins (200,000 dollars), and has the flattering satisfaction of realizing, together with a universal and enthusiastic approval of an appreciating public, an encouraging financial return on the outlay, by charging only half a florin (.20 cents) admission fee.

Here, an arrangement of the plants, more natural and thus more beautiful, than that in the Kew Palm-house, forms one of the chief attractions, but, as in all the older structures of this kind, the too great length in proportion to the width and the uniform level of the ground or floor, made full, or at least a better success in this direction, impossible. We also miss the aquatic plants and, besides a puerile, though larger than usual, "rockwork with cascade," we notice incongruities, such as vases with a yucca or a dracaena stuck into them; palms, over forty feet high, in tubs, which are by no means improved by being coated with bark; but what is decidedly most objectionable is the circumstance, that even here some genius, delighting in small things, has been permitted to intrude the paltry product of his talent for rag-quilting into this assemblage of the floral aristocracy of the tropics. (When will both gardeners and amateurs learn to understand where ribbon or mosaic planting, and how much of it, is proper?

The roof of this, in every essential respect, admirable conservatory, is appropriately simple and unpretending, not forcing itself unduly and first of all upon the visitor's eye. It is, what it always should be, - the mere shell of a sweet and delicious kernel.