22 Of the Superiority of the newly-invented Street Lamps.

torily by actual observation of the incomparably pure, beautiful, and brilliant light which it affords, the public may be convinced of the utility of the invention.

The proposed reduction of the number of Lamps (with the exception of corner Lamps) to only half the number now in use, would diminish the quantity and expense of breakage in the same proportion; which would be still further decreased by the strength of the globes, which being only half so deep as those now in use, are four times as strong; and by the security of the oil-holder, and from their being so constructed as to render the necessity of cleaning less frequent, and the operation more easy. The original cost of the improved Lamps necessary to illuminate a given space, would be less than that of the Lamps now in use; and the aggregate consumption of oil would be diminished, while the light is increased. Hence it is evident, that by a general adoption of the improved Lamps, the public would not only derive the benefit of a superior illumination, without additional charge; but, contrary to their usual experience of exclusive privileges, by patent or otherwise, would also, in this case, derive the farther advantage of a very considerable diminution of expense.

The improved Street Lamps, and Lamps of various applications, (in which the improved principles are introduced,) viz. Convoy, and Marine-Signal Lamps, Carriage Lamps, Reading Lamps, Magic Lanthorns, &c. and also Globes and Vases for ornamental purposes, may be seen and examined, by those who prefer ocular demonstration, at Mr. Brooks's, No. 110, Strand, opposite Exeterchange.

Application

Application of Larch Bark, to answer all the Purposes of Oak Bark, in Tanning Leather.

By THOMAS WHITE, Esq. of Woodlands, Durham.

From the TRANSACTIONS of the SOCIETY for the Encouragement of ARTS, MANUFACTURES, and COMMERCE.

The Lesser Gold Medal was voted by the Society to Mr. WHITE for this Communication.

IN

the year 1786, my deceased father did himself the honour of laying before the Society of Arts, &c. his re marks on the improvement of this place; and in a second letter, in 1796, he wrote some further observations; since which time, the plantations, as well as the place in general, have made great progress in beauty and im provement, which induces me to trouble you with a few ideas, that I flatter myself will be of importance to the country at large, as well as of private benefit to persons in possession of woods, which you will oblige me by laying before the Society.

As the trees have now advanced, as I have before observed, to a considerable size, we have been busy for some years in weeding them out to a timber distance; in doing which, lately, and whilst taking off the bark of some larch trees that were wanted for building purposes, our agent observed the nails of his fingers to be stained, which induced him to think, that the bark of this tree might be useful in tanning leather, a thought that struck the active mind of my father many years ago, when he was desirous of trying its virtues in this necessary and useful business, but was prevailed upon to give up the project, on being told, that a tree containing turpentine would not answer the purpose, his advisers thinking the

larch

larch was a species of the fir tribe, instead of the cedar. In consequence of this renovated idea, I was determined to have the most impartial trial made of the bark of the oak, and that of the larch; and in order to shew the latter no favour, I procured some of the best oak bark in the country, such as can rarely be purchased, and took that of the larch from a small young tree. I next purchased two calf skins, of the same value, weight, and quality, and put as much of the fine oak bark to one skin, as was applied of the larch bark to the other, both remaining in the pits the same time. During the operation, as we repeatedly weighed a certain measure of larch liquor against the oak, the latter always required an additional quantity to make the scales equal, which accounts for the skin tanned by larch being above one pound and a quarter heavier than the other, which it was when dried and ready for the currier, the increase being gradually perceptible during the whole business. Which of the two skins proved the best, I leave to the Society to determine, but I flatter myself that, exclusive of the additional weight of that produced from larch, the colour of it is preferable for gloves, saddles, boots, &c.

As I am proceeding with some other experiments, one of them will, I hope, prove which of the two infusions that the skins were tanned in, will afford the greatest weight of leather, in order to produce a fair test of the intrinsic value of both trees, when applied to tanning; the result of which I shall do myself the honour of laying before the Society at a future period.

It must be observed, that the bark of oak and birch, (the two kinds used to any extent), can only be taken off the trees for a very few weeks; whereas larch bark may be collected at any period during three parts of the year; and, I believe, with almost as good effect even in

winter;

winter; and as the bark is stript off this tree with very little trouble, the expense of doing it is much less than the oak. It is unnecessary for me to inform the Society, that as oak is daily decreasing in this country, so as to require a great annual importation, the larch trees (which I believe there is little doubt of being the cedar of Lebanon) is in a fair way to be as celebrated hereafter, as it was in former times.

In my professional exertions of laying out grounds, and planting by contract, I am constantly regretting the mischief done to woods, by the want of thinning them, which some of my employers tell me they neglect doing from the difficulty of finding sale for the weedings, which the probable source of consumption for the larch bark, will, I hope, entirely do away, and that this valuable species of tree, by being left at proper distances, will arrive at such perfection, as to be fit for most purposes, if not all, that oak is applied to, viz. in ship-building, &c.

It is my intention (if my professional pursuits will admit) to publish a small treatise on the management of woods, in general, collected from the practice of my late worthy father and myself, that I hope will be found useful.

I have sent, from Durham, by the mail coach, directed to you, in a paper parcel, the two skins, with specimens of the oak and larch barks, used in the process of tanning them; and also the currier's letter who dressed the skins, which, however, he does not think is to be laid before you.

I ain sorry that I have not been able to send before, two pieces of leather, of a strong quality, tanned with larch bark, and which, though perfectly useful for most purposes, would have continued to great advantage some time longer in the tan-pit for making soles of shoes. VOL. XXV.-SECOND SERIES.

E

With

With the specimens, I send a pair of gloves, and a remnant of leather, converted into shoes, both tanned with larch bark, by a person at Hexham, who told me that glovers would use nothing else, could they get a sufficient supply.

In addition to the equality that larch bark is upon with oak, in regard to its tanning as great weight of leather of every description, it has the advantage of being quicker, in its operation, and from its light colour, of being preferable, as mentioned before, for gloves, book-binding, &c.

It must be observed, that nothing has been introduced into the tan-pit to make leather firmer but bark.

The leather has not been five months in the tan-pit. Since I did myself the honour of sending to you, on the 26th ult. a parcel of leather, by the Charlotte coach, I am informed, that during my absence from home, and after you had done me the favour to request a specimen of strong leather, my tanner, to expedite the work, had applied occasionally warm water, in cold weather, which may have made the leather less firm than it would otherwise have been; the time that it was in the tan-pit, also, did not exceed four months. If you, therefore, think the leather is not sufficient to pass judgment upon, I will, when my strong hides are ready, send you a specimen of much superior quality. Mr. Curwen has just written to me for some leather, to whom I mentioned the disadvantage it laboured under.

After sending you the two first skins, I put a number of others, of equal weight and quality, into each of the two tan-pits, to try which bark would prove superior in the end, and found, on taking out the leather, on the same day, from each pit, although both were equally well tanned, that the larch liquid was the strongest, but did

T

not,