Fortified with a letter of introduction to Sir William J. Hooker, who fixed the hour of one o'clock to conduct us round these wonderful gardens and museum, it may well be supposed punctuality was among the virtues enlisted. The letter was from one of our most distinguished American botanists, a friend and correspondent of Sir William's, and most happily did it accomplish the object of affording the writer a day of unmingled enjoyment. At the appointed moment, our fascinating guide entered the gate - and, in company with an English lady and gentleman, who had earnestly solicited to be taken along to view these national gardens under such an instructor, we commenced our explorations.

Sir William J. Hooker, the "Director," is a Scotsman of prepossessing appearance, tall, of gentlemanly bearing, and full of information, which it seems to be his greatest pleasure to impart. He was frequently recognized and shaken by the hand by men of eminence and station, who, seeing his previous engagement, were content to follow in our wake and listen to his words of wisdom and information. At one moment, a gardener, who was going out on an exploring expedition of three years' duration for new plants, stepped up for his final instructions; they were brief and to the point, and the employer and employed parted as if for no longer a period, and with no more ceremony than if their separation was to have been for an hour.

"We will go first to the Economic Museum," said our polite guide, "that you may see my results." What follows is taken from our own memoranda as well as from a "guide" to the gardens issued in 1855, where we often find the very words used in verbal explanations; thus serving to complete a reminiscence which can never be forgotten.

The Museum was evidently a great hobby with the "Director," and we can perceive by the new catalogue that it so continues. It is a depository for all kinds of useful and curious vegetable products, which neither the living plants of the garden nor the specimens in the Herbarium could exhibit. It renders great service, not only to the scientific botanist, but to the merchant, the manufacturer, the physician, the chemist, the druggist, the dyer, the carpenter, and cabinet-maker! and artisans of every description, who may here find the raw material (and the manufactured article), employed in their several professions, correctly named, and accompanied by some account of its origin, history, native country, etc, either attached to the specimens or recorded in a popular catalogue. Nobly has this project been carried out, and the aid from every source has been an evidence of its utility and popularity. At this moment, a number of our friends and neighbors are preparing a collection of specimens of American woods for this museum, under the direction of Dr. William Darlington, of this State. The British Government have given facilities of transport for everything going to Kew. The elder Mr. Canard came up for a friendly shake of the hand, and we were introduced to him as "My kind friend who transports for me without any charge whatever".

To a commercial nation, ready to seize upon every article that can be turned to economic account in manufactures, this scheme has proved of immense importance; textile fibres, gums, resins, dyestuffs, starches, oils, woods, tannins, drugs, food for man, basket-work, all the products of straws and grasses are assembled. Let us listen to Sir William's fluent talk, which cannot dwell long on anything, so numerous are the objects we have to view.

Here are the fruits of the yellow water-lily, nuphar lutea; the leaves are said to be styptic; the flowers have a brandy-like smell, and the pistil is shaped like a flask, whence the name of "Brandy-bottle." Next is the poppy family. Six millions and a half pounds of opium are annually bought up as a source of revenue to the East India Company. Little more than one hundred thousand pounds is required for England per annum, but it is calculated that twenty millions of pounds are annually consumed by mankind. You see all the processes of manufacture in the plant, the pictures, the implements, and the article in all its stages. - Horseradish-tree family, order moringaceae. This natural order, of doubtful position, is now generally placed near the violet family; it is confined to one genus, moringa. Ben-oil, pods and seeds of moringa pterygosperma; an Indian tree, cultivated in Jamaica. Its pure fixed oil is much used by perfumers on account of its not easily becoming rancid, and by watchmakers, because it does not freeze.

The roots have exactly the flavor of horseradish; pods used in curries. - Manna of Mount Sinai; it is an exudation from tamarisk mamifera, occasioned by an insect, a species of coccus which inhabits the shrub, and this manna consists wholly of pure mucilaginous sugar. - Here is a native shoe-blacking! among the cottons; the beautiful flowers of Hibiscus Rosa-Sinensis are used by the Chinese to blacken their eyebrows and their shoes. Soapwort, saponaria officinalis; bruised and agitated in water, it raises a lather like soap, and may be used as a substitute for it. Cotton specimens of every description, and its manufactures. Spun to the fineness of eleven hundred and forty-five miles per pound, it is too fine for anything but to be looked at. You are an American, and want to see something new. - This is the Boab, or monkey-bread fruit, adansonia digitata; the product of one of the most remarkable trees in the world. The wood is pale, light-colored, and so soft that in Abyssinia the wild bees perforate and lodge their honey in the trunk, which honey is considered the best in the country.

On the west coast, its trunks are hollowed by the natives, and their dead, deposited therein, where they become mummies. - Nuts of the Kola, sterculia acuminata, Africa and West Indies; they have a pleasant, aromatic taste, and are much esteemed by the negroes as promoting digestion; they also prevent sleep, and are used by the native watchmen to keep themselves awake. Bags of the sterculia villosa; they are quickly made, by steeping logs and stripping off the bark; used for conveying goods in the Goa country.

Jute paper, excellent and recently prepared from old gunny bags; from the corchorus capsularis. A manufacturer of the finest pocket-handkerchiefs has discovered in the fibre of the despised gunny-bag, a material of immense value - you see the great fineness of the handkerchiefs. - Tea family. Here is "the Old Man's Eyebrow Tea;" it is done up, as you see, in short twisted sticks, and perhaps bears allusion to the legend of some Chinese saint tearing off his eyebrows and throwing them on the ground, where they sprouted into tea-plants; representations of this wonderful transformation you see on those Chinese screens! - Order, aurantiacse, orange family. They are looked upon as the golden fruits of the Hesperides, whence Jussieu called this family Hesperideae. Here are all the oils of the family, and the toothpicks and walking-canes so much esteemed, made from the wood in Madeira and Rio Janeiro. - Product of the butter or tallow-tree, pentadesma butyracea; a yellow fatty substance. - You see all the products of the coca-tree, used extensively by the laboring classes, especially the miners of Peru, for its remarkable powers in stimulating the nervous system; in this respect, resembling opium__And here among the maple sugars, Ac, is an American clothes peg! made of maple-wood (an article still a great curiosity with many English people from its strong contrast to their clumsy peg made in three pieces and bound with tin, which rusts, and iron-moulds the clothes!). - Look at the various products of mahogany! A single log has been sold for fifteen hundred dollara. - Zante currants; they are a grape of the vitis vinifera, and originally from Corinth.

So we proceed, talk succeeding talk, and every word having its meaning. The order geraniacese, Cranesbill family. You know the geraniums and pelargoniums, but do you know that one species, the spinosum, is so resinous that the dead stems become masses of resin in the sands of South Africa, retaining their form, and they burn like a torch, giving out a most agreeable odor f - Here you see the large cotyledons of simaba cedron, from New Granada, where it is considered to supersede the sulphate of quinine. - The wood and jujubes of zizyphus vulgaris. Z. spina Christi is considered by some to be the thorn with which our Saviour was crowned. - Pease earth-nuts; tubers of lathyrds tuberosus, much eaten in Germany during the period of the potato panic. - Flower buds of sophora japonica, much used as a dye in China and Japan. - Mimoseae; ordeal, or red water-tree bark. The red juice is given in large draughts to those accused of crime, and those who can withstand the ordeal, are innocent, but the priests know how to mix it to kill or not! - Mangrove family; the branches send down aerial roots; the seed germinates while still attached to the parent, and falls down a young plant. - Monkey-pot family; the lidless capsule is used for catching monkeys.

Sugar is put in the small opening which enlarges within, so that when the animal has grasped the sugar with his paw, he is unable to extract it, and the very heavy seed-vessel acts as a clog to him, from which he cannot disentangle himself.

Water-chestnut family; some with a little imagination, or a very little assistance from a knife, are very much in the shape of a bull's head, are much eaten. - Papaw fruit, carica papaya, South American. The juice of the entire plant has the property of making old and tough meat tender. - When we visited Eew, Sir William was very desirous of procuring the Chinese rice-paper plant, and we see he has lately succeeded. It is the pith of the aralia papyrifera, from Formosa, cut into small sheets, and it is a great article of commerce with the Chinese. - Prepared coffee-leaves, much used in Sumatra, instead of the berry. - Chinese insect wax, or pela, with the insect; this wais imported from China, and candles are dipped in it, to render their exterior hard. - Guttapercha; the tree, the juice; numerous manufactured articles from it; in fact, the whole processes are before you. - The tree that produces Cuba bast for tying up cigars has not yet been procured, and is much wanted. - Jumping or moving seeds. Lobes of a capsule of some euphor-biaceous plant, from the Pacific side of South America, which move by jerks, and have almost a jumping property.

This is found to be occasioned by the sudden and peristaltic movements of an insect within, and of which the egg must have been deposited in the state of the flower, for the shell has no perceptible aperture or wound whatever.

But we must not trespass too much, to-day, on our limited space; next month some still more remarkable things may find a place, with the history of our English lady going down on her knees with parasol hoisted, fairly overcome with fatigue, as, indeed, any one might well be who attempted to follow the indefatigable "director" from one o'clock till a late sunset.