thorns. This border fhould be at least two feet broad within the hedge, and made hollow, the better to retain the moisture. On this plant your thorns in thicknefs proportioned to the fize of your plants; for the common run of thorns three or four. years old, fix inches diftance is the general rule, but for ftout ones that have been twice removed, and confequently have abundance of roots, a foot will be clofe enough. These thorns ought not to be planted upright, but should be laid as near as may be in a horizontal pofition, fo that the top of the one extend as far, and be just above the root of the other. This method of planting, in place of a few vigorous rambling hoots from the top of the plant, which is ufually the cafe with fuch as are planted perpendicular, will make them brush from the bottom like a fan, and in two years, by keeping them as has been directed, they will be fo close that a small bird cannot get through them. But let it be obferved, I do not mean this to be practifed in the nursery, nor even in the field, for fuch as are above fix or seven years old, or that are planted above the height of two, or two and a half feet high, as this oblique pofition, in large brushy plants, will not admit of their roots having the fame ftability to refift the winds as those placed upright.'

Before this fubject is difmiffed, a remark may be produced from the chapter on the yew-tree, that may be worth the confideration of the inhabitants of populous towns. I fhall, fays Mr. Boutcher, only add one very material quality more, though not related by any writer fo far as I know, and which is, that the wooden parts of a bed made of yew, will moft certainly not be Approached by bugs. This is a truth, confirmed to me by the experience of trees I had cut down and used myself in that way.'

We are informed, in a poftfcript to this treatife, that if the prefent performance meets with a favourable reception from the Public, (of which, from its apparent merit, we have little doubt) the Author will foon publifh his improvements in the culture of Fruit-trees; in which, he affures us, he has had great variety of experience. He does not fcruple to add, that by following the plan which he proposes to communicate to the Public, we hall, to his certain knowledge, eat at least as good fruit at Edinburgh as they now do at London,'-and, as near as he can judge, much about as good at London as they do at Paris. And this, he declares, may be done with no ⚫ additional expence to the ufual culture, worth naming.'

ART. IV. Philofophical Tranfactions, Vol. LXV. For the Year 1775Part 1. 4to. 7 s. 6 d. fewed. L. Davis.

PAPERS relating to ANIMAL ELECTRICITY. Article 1. Experiments on the Torpedo, made at Leghorn. By Dr. John Ingenhoufz, F. R. S. &c.

HESE experiments confirm, fo far as they extend, those lately published in the Tranfactions by Mr. Walfh*, to which they were fubfequent. The following are the most material results of the Author's trials:

Having infulated himself, with a torpedo held in his hand, fo that his thumbs gently prefied the upper fide of those two foft bodies at the fide of the head, called mufculi falcati by Redi and Lorenzini, while his forefingers preffed the oppofite fide; he did not exhibit the leaft figns of being electrified, whether the fifh gave him a fhock or not.-The torpedo alone being infulated did not attract light bodies; nor did it communicate any charge to a coated vial applied to it.-When the fish gave the fhock in the dark, no fpark was perceived, nor was any crackling noife heard.-No fhock was given when the Author applied a brafs chain, inftead of his thumb, to the fide of the fifh:-but he does not feem to know, as is hinted in a note, that the torpedinal commotion, which would have doubtlefs paffed through a rod of metal, might not be able to force a paffage through the numerous interruptions of continuity in a brafs chain. It is to be obferved that the largeft of the torpedos, on which thefe experiments were made, did not exceed a foot in length.

Article 10. Experiments and Obfervations on the Gymnotus Electricus, or Electrical Eel. By Hugh Williamfon, M. D.

The Gymnotus Electricus of South America appears to poffefs electrical powers greatly fuperior to thofe of the European torpedo. It is even related in the following article that fome of thefe fish have been feen in Surinam river, upwards of twenty feet long, whofe ftroke or fhock was inftantly fatal to thofe who unluckily received it. That on which the Author made the experiments related in this article, was three feet feven inches long, and had been brought from Guiana to Philadel phia, where it exhibited the following among other phenomena.

On putting a fmall living fish into the veffel in which it fwam, it was fuddenly ftunned and killed by it. The effect was evidently produced by a concuffion which was felt by the Author, whofe fingers were dipped into the water, at the very moment that the fish was fhocked by it.-Eight or ten perfons forming a circle were all fhocked by it, provided the first in the feries touched the eel, and the laft put his hand into the water in which it fwam.-The commotion given by it was con

* See Review, vol. li. See the Index.

veyed through the fame metallic or other conductors as convey the electric fluid; and was intercepted by the common nonconductors of that fluid. It was fometimes ftrong enough to pafs through a brafs chain, if the links were not too numerous, and the chain tenfe:-but the following experiment would furnish the most complete proof of the identity of the torpedinal and electrical commotions, if the Author had not expreffed himfelf dubioufly in relating it.

Two pieces of brafs wire, rounded at their ends, and of the thickness of a crow-quill, were made part of the circuit, which was however interrupted by placing their extremities oppofite to each other in a frame of wood, fo as that by means of a fcrew they might be fixed at different diftances from each other. When they were feparated one-fiftieth part of an inch, no fhock was felt by thofe who held the other extremities of the wires but when the interval between them was no greater than the thickness of double-poft paper, the concuffion was felt; fo that, fays the Author, it doubtlefs leaped from the point of one wire to the other, though,' he adds, we were not fo fortunate as to render the fparks generally vifible.'

Those who are most converfant in this fubject, and who are best acquainted with the defign and importance of this experiment, will be moft hurt by the dubious and inexplicit manner in which the Author relates the refult of it. From the laftmentioned expreffion the Reader will certainly be inclined to conclude that sparks were, at leaft, fometimes vifible in the interval between the extremities of the two wires. If this were the cafe, an appearance of fuch importance, never yet obferved, though carefully inquired into, by others, ought undoubtedly to have been defcribed in a more pofitive and decifive manner: but from what follows, to the end of the paragraph, the doubting Reader is led to fufpect that the Sparks, inftead of having been only not generally visible, were not feen at all. For after mentioning the difficulty of exciting this fish, and its bad ftate of health, the Author concludes the paragraph by adding that perhaps fire emitted by eels lately taken, might be rendered vifible.' Article 11. An Account of the Gymnotus Electricus, &c. By Dr. Alexander Garden, M. D.

In this Article the Author pretty minutely defcribes the form, fize, and other external appearances of the largest of five electrical eels, which he examined at Charles-Town in South-Carolina, whither they had been brought from Surinam. It is not eafy, as he obferves, and it certainly cannot be a pleasant tafk, to examine very accurately an animal fo uncommonly irritable and hafty, and endowed with powers fo very inconvenient to the inquirer. His experiments confirm many of the obfervations

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obfervations already made by others. They feem particularly to prove the neceffity of forming a proper communication between the different parts of the fish, in order to receive a fhock from it; though fome perfons have affirmed that they have been fhocked on touching the fish with one hand only. This however may have happened, by means of fome unobferved communication, which the operator might have with the vessel or the water in which the fish was contained.

CHEMISTRY.

Article 4. The Defcription of an Apparatus for impregnating Water with Fixed Air; and of the Manner of conducting that Procefs. By John Mervin Nooth, M. D. F. R. S.

The procefs for impregnating water with fixed air is applicable to fo many ufeful purpofes in philofophy, and particularly in chemistry and medicine; that we wish to make this new method of conducting it generally known. It is not perhaps eafy to convey a clear idea of this apparatus, without the drawing that accompanies the prefent article. The philofophical Reader, however, will probably comprehend the general principles on which it is conftructed from the following defcription.

The apparatus confifts of three diftinct glass veffels, in the first or lowest of which the effervefcing fubftances are to be put. The fecond or middle veffel, which contains the water or other fluid that is to be impregnated with fixed air, is of a globular form, refembling an electrical globe; having two necks, the loweft of which (accurately ground fo as to make the juncture air-tight) is inferted into the mouth of the lower veffel; while its upper neck receives the third or uppermost veffel, which is likewife of a globular form; except that it terminates, at its inferior extremity, in a bent tube, which defcends into the cavity of the middle veffel. Its upper neck has a ground glafs ftopper adapted to it.

The middle glafs being filled with the water that is to be impregnated, and the empty upper veffel being fitted to it; fome diluted vitriolic acid is to be put into the loweft glafs, and fome powdered chalk is to be added to it. The two upper conjoined veffels are now to be adapted to the lower veffel. The fixed air expelled from the chalk paffes up into the water contained in the middle glafs, through its lower neck, in which a valve is placed, which gives a pafiage to the air, but prevents the defcent of the fuperincumbent water. In proportion as the fixed air rifes into the middle vefiel, it forces up an equal bulk of water, through the curve tube, into the upper one. The upper vellel, in fact, or rather the water thus driven up into it, may be confidered as a kind of liquid moveable stopper; fecluding the water contained in the middle vcffel from all imme

diate communication with the atmosphere; firft afcending and yielding to the influx of fixed air into the middle veffel, and afterwards, on the absorption of the fixed air, defcending and occupying the space deferted by it.

When the greatest part of the fixed air has been abforbed by the water in the middle veffel, the remaining and lefs foluble part of it may be let out, by lifting up the higheft veffel, and fuffering all the water contained in it to descend, and again fill the middle glass. Fresh chalk may then be thrown into the lower veffel; and the two upper glaffes are to be inftantly replaced. It is evident, from the very principles on which this machine is conftructed, that, in order fully to faturate the water with fixed air, the preceding procels must be repeated three or four times. It is fcarce neceffary to add that the impregnation may be greatly accelerated by occafionally removing the two conjoined upper veffels from the lower one, and forcibly agitating the water and fixed air together.

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From the experience that we have had of this apparatus, which has fince received fome improvements from Mr. Parker in Fleet street, where it is fold, it appears to us a commodious and elegant machine; well adapted, in particular, to the use of those who are not accuftomed to the performance of philofophical experiments, and who would choose to manufacture their own Pyrmont water; or who may happen to be prejudiced against the ufe of a bladder, which is employed in one of the two methods of impregnating water, invented by Dr. Priestley. That method however poffeffes fome peculiar advantages in the hands of an experimental philofopher; nor can we help thinking that the Author's objection to the ufe of a bladder (as communicating to the impregnated water an offenfive and urinous flavour, which is, in general, fo predominant that it cannot be fwallowed without fome degree of reluctance') is fomewhat finical, and founded rather upon whim than fact.At least, we have never found ourselves poffeffed of the guftus eruditus in a fufficient degree, to make us fenfible of the urinous taste here complained of, though we have made numerous trials with Dr. Priestley's apparatus. In fact, if the Author ufes the term urinous according to its common acceptation; we cannot conceive how a taste or flavour of that kind can be communicated by a clean and dry bladder. If, with the chemifts, he employs it as fynonimous to alcaline or lixivial; it is certain that fixed air is fo far from communicating to water an alcaline or lixivial flavour, acquired from fubftances pofieffing that quality, that, on the contrary, it completely deftroys it; as we thall, ere long, have occafion to demonftrate.

Dr. Nooth's apparatus is, however, ingenioufly imagined, and fully answers its principal purpose, of preparing an excel

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