worthless ones would damage the business irreparably. They should be of brass, and placed in frames of wood, which will not be easily affected by atmospheric changes. Common pine wood, veneered with mahogany, have answered well. Spring clocks will not succeed. Some of this description, sent from New York, cannot be kept in repair; whilst a quantity of clocks moved by weights, manufactured chiefly in Connecticut, imported into China above seven years ago, have proved good time-pieces, and give no trouble.

With regard to the external appearance, on which so much depends, I would advise that, in every case, there be as much of the works exposed as possible through an opening in the dial plate. A Chinaman not only wishes to see what he is buying, but what is going on in his instruments when bought; and, as his countrymen have the merit of being extreme utilitarians, mirrors in the lower part of the door will be generally preferred to any other ornament. Some, however, should be ornamented at this point for the sake of variety; and perhaps nothing would please more than such a grouping of objects by the artist as would represent a river, bringing into view a steamboat and a sloop, and on the banks a railroad, locomotive, and cars; a steepled church, or a many storied hotel, in the distance; and a stage coach also. Or another interesting device would be afforded by a representation of the solar system; but this would need to be accompanied with several Chinese characters. It is of primary importance that a particular description of the manuer of using the clock, the mode of putting it up, setting it off, winding up, and regulating, should be given. These directions, which should be more minute than if designed for English readers, can be translated and printed very easily in this country. But there would be no difficulty in printing the directions by means of wooden blocks in the manufactory at home. In copying the characters for the dial extreme care is requisite that every stroke and each line should be represented exactly as given in the diagram. Astronomical characters or descriptions of any kind which may be needed by individuals trying the experiment of clock-making for China, I shall furnish most cheerfully, for the privilege of increasing the utility of the instrument by introducing with them a few passages of sacred Scripture.

It may be asked, why, if such a clock be needed by the Chinese, they have never constructed one for themselves? It is certainly marvellous that they should manufacture clocks, including dial plates, and always employ Roman figures, and follow the reckonings of foreigners, which so few of them are able to comprehend, and which by all are considered mysterious and outlandish. It is only to be accounted for on the ground of their limited inventive abilities and high powers of imitation. That a time-piece of this description would be in demand in China, I am per fectly satisfied from inquiries made of natives in various quarters. Chinese merchants say that they should be retailed at about $5 or $6 each. If I recollect rightly, they can be made in Connecticut at $2 50, which would afford sufficient profit both for the mechanic and merchant. NINGPO, July 4, 1851.

MEAT BISCUIT.

Extract from the Lecture of Professor Lindley, on substances used as Food: Illustrated by the Great Exhibition.

What is more important than all other preserved provisions is the article to which I must next request attention. A great deal of interest was excited when the contents of the Exhibition first became knownand it did not diminish afterwards-by a certain meat biscuit introduced among the American exhibitions from Texas by Mr. Gail Borden. We were told that its nutritive properties were of a very high order. It was said that ten pounds weight of it would be sufficient for the subsistence of an active man for thirty days; that it had been used in the American navy, and had been found to sustain the strength of the men to whom it had been given in a remarkable degree. Statements were made to us, which have since been corroborated, that it would keep perfectly well without change under disadvantageous circumstances. Colonel Sumner, an officer in the United States dragoons, who had seen it used during field operations, says he is sure he could live upon it for months and retain his health and strength. The inventor, he says, names five ounces a day as the quantity for the support of a man; but he (Colonel Sumner) could not use more than four ounces, made into soup, with nothing whatever added to it. The substance of these statements may

be said to amount to this: that Borden's meat-biscuit is a material not liable to undergo change, is very light, very portable, and extremely nutricious. A specimen, placed in the hands of Dr. Playfair for examination, was reported by him to contain 32 per cent. of flesh-forming principles; for it is a composition of meat-the essence of meat-and the finest kind of flour. Dr. Playfair stated that the starch was unchanged; that, consequently, there could have been no putrescence in the meat employed in its preparation, and that the biscuit was in "all respects excellent." It was tasted: I tasted it-the jury and others tasted it-and we all found nothing in it which the most fastidious person could complain of. It required salt, or some other condiment, as all these preparations do, to make them savory. This meat biscuit, as I said just now, was reported to be capable of keeping well; and this might well be true, because no foreign matter had been introduced into its composition. There was no salt to absorb moisture, and nothing else to interfere with the property of flour or of essence of meat. These biscuits are prepared by boiling down the best fresh beef that can be procured in Texas, and mixing it in certain proportions with the finest flour that can be there obtained. It is stated that the essence of five pounds of good meat is estimated to be contained in one pound of biscuit. That it is a material of the highest value there can be no doubt. To what extent its value may go nothing but time can decide; but I think I am justified in looking upon it as one of the most important substances which this Exhibition has brought to our knowledge. When we consider that by this method, in such places as Buenos Ayres, animals which are there of little or no value, instead of being destroyed, as they often are, for their bones, may be boiled down and mixed with the flour which all such countries produce, and so converted into a substance of such

durability that it may be preserved with the greatest ease, and sent to distant countries, it seems as if a new means of subsistence was actually offered to us. Take the Argentine republic, take Australia, and consider what they do with their meat there in time of drought, when they cannot get rid of it while it is fresh. They may boil it down, and mix the essence with flour, (and we know they have the finest in the world,) and so prepare a substance that can be preserved for times when food is not so plentiful, or sent to countries where it is always more difficult to procure food. Is not this a very great gain?

IX.

THE WORLD'S EXPOSITION OF 1851.

Presuming that an examination of, and a report on, the works of industry and art to be exhibited at the World's Fair would be advantageous to the agricultural and manufacturing interests of the Union, the following communication on the subject was addressed to the Secretary of the Interior:

PATENT OFFICE, February 10, 1851.

SIR: The present year will be one of unprecedented interest as regards the arts and industry of the world. The natural productions, the plastic arts, and the results of the inventive ingenuity of all nations-their machinery and manufactures-will be displayed side by side, their respective merits scrutinized, and prizes, it is announced, awarded by discriminating and impartial judges.

The United States have been invited to participate in the great concourse of material sources and productive skill, and, judging from the arrangements already made, they are likely to be largely represented in every department.

A report of such an exhibition of the skill, industry, and ingenuity of the world would be of the highest value to this Office, even if viewed only in relation to the various branches of invention of which it is the primary function of the Office to take cognizance. In discharging the daily duties of examining and deciding upon inventions, many questions arise which can only be decided by extensive researches among books, or in workshops and factories. The works pertaining to the arts contained in the Library of the Patent Office are too few in number to give all the information required, and, even if much more numerous, they would not serve to make known all the inventions that have been patented in foreign countries, of which many are not published till the patents expire, and others only in abstracts or imperfect descriptions.

Hundreds of minor devices and processes, simple and seemingly trifling accessories of staple mechanism, will be found there, of which it is equally important for this Office to be informed. These constitute a class of contrivances not found in books, and a knowledge of them is therefore highly desirable. Instances have occurred where patents have been issued for such, because evidence of their use in work-shops was lacking. They often present remarkable examples of simplicity and efficiency, and of neat turns of mechanical thought, which few besides practical men can appreciate. Of course none but the eye of one familiar with the details of modern manufactures and arts could detect them.

The usefulness of such a report, however, would not be confined to the immediate operations and duties of this Office. If prepared with due

In the sixth century, an instrument was in use which indicated the course of time by the weight of water, as it gradually came from the beak of a bird and was received into a vessel on a balance, every pound representing a kih. About this time mercury began to be employed, instead of water, which rendered the aid of heat in winter unnecessary. Changes were made also in the relative number of kih for day and night, so as to vary with the seasons.

As in Europe, monks of the Roman church devoted considerable attention to mechanical inventions, especially in the construction of instruments for measuring time for the regulation of their worship and vigils; in like manner, also, Buddhist monks, in their silent retreats, but at an earlier period, similarly occupied themselves, and for the same purposes. Several instruments, designed as time-pieces, the invention of priests, are mentioned in Chinese history. They present nothing novel, however, with the exception of one, which is nothing more than a perforated copper vessel, placed in a tube of water, which gradually filled and sunk every hour, requiring, of course, frequent attention. Although their knowledge of hydrodynamics has ever been very limited, the Chinese appear to have been the first to devise that form of clepsydra to which, the term water-clock is alone properly applied; that is to say, composed of apparatus which rendered watching unnecessary by striking the hours. Until the commencement of the eighth century, the persons employed to watch the clepsydra in palaces and public places struck bells or drums every kih; but at this period a clock was constructed, consisting of four vessels, with machinery which caused a drum to be struck by day, and a bell by night, to indicate the hours and watches. No description of the works of this interesting invention can be found. It is possible, however, that the Saracens may have anticipated them in this invention of water-clocks.

In the history of the Tong dynasty, (620-907,) it is stated that in the Fahlin country, (which, in this instance, doubtlessly means Persia, though the best living authority amongst the Chinese makes it Judea,) there was a clepsydra on a terrace near the palace, formed of a balance, which contained twelve metallic or golden balls, one of which fell every hour on a bell, and thus struck the hours correctly. It is not improbable that this instrument is identical with the celebrated one which the king of Persia sent, in 807, to Charlemagne.

In 980 an astronomer, named Tsiang, made an improvement on all former instruments, and which, considering the period, was a remarkable specimen of art. The machine, which was in a sort of miniature terrace, was ten feet high, divided into three stories, the work being in the middle. Twelve images of men, one for every hour, appeared in turn before an opening in the terrace; another set of automata struck the twelve hours, and the kih, or eighths, of such hours. These figures occupied the lower story; the upper was devoted to astronomy, where there was an orrery in motion, which, it is obvious, must have rendered complex machinery necessary. We are only told that it had oblique, perpendicular, and horizontal wheels, and that it was kept in motion by falling water. As the Saracens had reached China by sea at the close of the eighth century, and by land at an earlier period, some assistance may have been derived from them in the construction of this instrument; but I am disposed to consider it wholly Chinese. Beckman, after much learned research, ascribes the invention of clocks to the Saracens, and the first