In the apparatus, known by the name of the electrical mas gazine, constructed fo that the tube may be taken away and replaced at pleasure, the abbé inclofed twelve kinds of feeds, in as many parcels, covered with tin foil. After eftablishing the neceffary communications, the magazine was insulated, and charged, during fix days, every two hours; previous to every fresh charge, it was difcharged, and the explosion showed that the electricity was conftant. Twelve fimilar parcels were plac ed in the fame place, without being electrified, as ftandards, These were carefully fown with accurate diftinctions, and the refult was, that the electrified feeds appeared fooner than those not electrified, often by two days, generally by more than one day, out of ten. In the fubfequent years a little variation occurred, but the difference was always decidedly in favour of the electrified feeds. The experiments were varied, by immerfing the feeds in water, during the application of the electri city, which was continued two days: the appearance of the plants not electrified was at least a day and a half later, and their growth was flower: the beans and peas were fometimes two days earlier than the standard. Some feeds were next fufpended in metallic coverings to the prime conductor for feveral days, and thefe were alfo much earlier than the ftandard; others were included in an electrophorus, with a fimilar effect.

The electricity was next employed after the feeds were fown. Some grains of mustard-feed were fown in two little bowls of tin, and each put into an electrical jar, fo that the orifices of the jar and the bowl were on a level. The jars were then charged, and the bowls were taken out, when the electrometer fhowed a diminution of the electricity. This operation was continued from eight to eleven in the morning, and from two to five in the afternoon; the rest of the time they were placed in a window. The jars were electrified three following days, and two bowls, as ftandards, were managed and placed exactly the fame, except that they were not electrified. The difference in the time of the appearance of the plants was from two days and a half to near four days. The feeds were then fown in non electrified jars, and the electricity was applied after they had come up. The difference in their growth was confpicuous on the first day, and after four days it amounted to nearly half an inch, for fo much did the plants in the electrified jar exceed the standard. After the electricity ceafed, the plants fubjected to its influence continued for one day to increafe fenfibly in height, while those of the ftandard were nearly stationary. Thofe plants which feemed to grow very flowly, foon equalled the others, when a metallic point was held over them from time to time. The more rapid vegetation was alfo confpicuous, when by means of a metallic cover the fluid paffed more freely and infenfibly into the bowl. Some other more minute variations we must omit ; but may obferve, that electricity is found to increase the vege tation of the roots as well as of the leaves,

The

The abbé next confiders natural electricity, and objects to fome of M. Ingenhouz' experiments, though he declines an fwering them particularly, as it would render his memoir too long. Our author had formerly mentioned an infulated conductor in his garden, and obferved that plants within its sphere flourished very rapidly. Since that time he has repeated his obfervations with the fame fuccefs, taking for his standards fimilar plants in the vicinity, where the electrometer fhowed no marks of electricity. The abbé varied thefe experiments alfo with equal fuccefs, and points out the neceffity of a minute attention to every circumftance, particularly placing the pots not infulated on a stand of the fame height with thofe that were in fulated. The jafmin, which grows with fuch furprifing luxu riance against the maft which fupports the conductor at the feat of the fenator Quirini, on the banks of the Brenta, is again introduced. M. Ingenhouz had fufpected that this conductor was not infulated; but, on thie fubject, he has retracted his fufpicion, and allowed it to be fo. The calamint and the creffes, which grew near a conductor, and feemed not to feel its influence, are therefore of no importance in the difpute, as that conductor was infulated. The rains alfo conduct electricity from the clouds, and the abbé accounts for the little comparative utility of artificial watering, compared with the influence of rain, from this circumftance. He concludes with answering M Ingenhouz' objections in this refpect.

Though we have mentioned M. Ingenhouz' allowance ref pecting the conductor, we ought to obferve, that he has replied to the circumftance of this extraordinary jafmin, though not in a very fatisfactory manner. Plants, he obferves, are either humble or luxuriant, according to their refpective fituations. A vine, in an unfupported state, is humble; but, when it has the affiftance of a high tree, it equals the height of its fupporter. The jafmin, he thinks, may be a plant of the climbing kind; but in this refpect he is mistaken: the jafmin never climbs, but when tall it requires a fupport, and it is not probable that this remarkably high plant is compared with the dwarf standards. In other refpects he ftill contends for his firft opinion, and remarks, that his trees, which were furnished with conductors, produced their leaves in the fubfequent years at the fame period as before; and though fome of the conductors were loft, no variation was obferved. In reality, the conductors feemed, in his opinion, to have very little, if any, influence,

M. Ingenhouz has found an able fupporter in M. Rouland, profeffor of natural and experimental philofophy at Paris. He gives a good hiftory of the different opinions on this fubject, and tells us that he proceeded to examine it by experiment. He floated three circular pieces of cork, in a tea faucer of water, and in thefe, wrapped in bibulous paper, he fowed the feeds of creffes. One of thefe corks he electrified pofitively, the other negatively, and the third remained in its natural ftate: in one

place

place only is it obferved that this third cork was out of the sphere of the electricity of the two others; but fo obvious a circumfance, M. Rouland undoubtedly attended to. In all the experiments no difference appeared in the vegetable process. The plants in each dick came up at the fame time; though, if he had fown fewer feeds (his number was 100), he fhould have fuf pected, he fays, that there was fome variation. M. Bertholon, it must be allowed, fowed fewer; but the conftant uniformity of his results seems to preclude any fufpicion of mistake from this fource. In one inftance, a few of the plants, electrified nenatively, died, and in another, this accident happened to fome which were electrified pofitively, fo that thefe events are pro. bably of little importance, and had little connection with the refults.

M. Bertholon, on the other hand, has gained an able assistant in the abbé d'Ormoy, and his experiments feem to have been conducted with great accuracy: fome of them are very convincing. He first electrified his feeds by placing them on the magical picture, but they were too few to render the experiment decifive. Some feeds, however, of an English rofe-tree were electrified, and, in former trials in the common way, these feeds never germinated. Five out of twelve, however, grew, while the non electrified feeds never appeared: when previously macerated in water, and watered with electrified water, three out of twelve grew, but the standards never germinated. Our author varied his experiments with lupins, and by giving the feeds, previously, different fhocks during the electrization: the vegetation of thefe alfo was confiderably accelerated. It appeared too that the plants, produced from electrified feeds, were not only larger, ftronger, and of a more vivid colour, but that they refifted longer, being deprived of water.

The abbé next electrified feeds in different manners; viz. by placing them on the magical picture, in a covering of tin, paffing the electric fluid through them in fhocks, and fimply placing them on the picture, without any envelope. The vegetation feemed to be accelerated in the fame order in which we have defcribed the experiment: the strongest plants were thofe placed on the picture in the metallic covering. A little obfcurity retarded the vegetation in the non electrified plants, though M. Ingenhouz fuppofed it might have a contrary effect. Our author varied his experiments, and the feeds fown in many different ways, but always with fimilar fuccefs. The electrified plants were of a greater fize, fuller of leaves, and more robuft. Silk-worms alfo, placed on the magical picture in the early part of their existence, and afterwards on a cake of rezin, which communicated with the prime conductor, grew much fafter than the others, fpun earlier, and were not fubject to diseases, though fed on damp leaves.

Another difpute which the electrical fluid has raised on the continent, we need only mention: the defenders and oppofers

of

of the opinion have nearly equal merit. In the year 1789, a memoir was published to fhow that the congelation of water was owing to the introduction of the electrical fluid, and this fyftem has excited fome oppofition, though it has fcarcely in any inftance contributed to the progress of fcience.

M. Goddart's memoir, on the fubject of ground-ice, has been answered, perhaps a little too haughtily, by J. H. Pott, of Laufanne, He has demonstrated, he says, that the thermometer does not fink below the congealing point when immerfed, in the coldeft winters, below the ice on the furface; that the 6 or 7 degrees of greater cold, which produce ice of about two thirds of an inch in a running ftream, will not freeze water in a bottle at the depth of an inch; that another bottle, funk to the depth of 3 feet in our canal, refifted the horrible cold of 114 below o, which occurred the last day of the year 1783.' These are the facts on which our author refts, and he has proceeded to explain these facts, and to answer the arguments adduced by Dr. Goddart: it would be ufelefs to follow him at length; and, indeed, he has omitted the principal circumstance. When he allows, with Hales, that in running rivers, the colder particles falling down, will foon bring the water to an uniform heat, he ought to have given fome reason, why the ftones and other bodies at the bottom, which act as points from which the crystallization ufually commences with more facility, should not have the fame effect, in this inftance. When once ice is produced, it greatly haftens the production of other ice, and in fuch inftances the water will more readily freeze at the bottom than on the furface.

The uniform temperature of deep rivers is connected in some degree with that of caverns, and brings to our recollection the very curious experiments of M. Caffini on the heat of the caverns at Paris; a heat fo conftant, that it has been employed as a fixed point, from which thermometers have been graduated. From the obfervations of M. de la Hire, we have been taught to confider the heat as nearly, if not exactly, uniform in these caves, though fome other observations of M. Caffini, the great grandfather of our author, fill exift, which speak a different language. On the 24th of September, 1671, he put a thermometer into these caverns, which continued ftationary during the whole month of October and November. On the 7th of December it was found a little below the mark, and, on the 21ft, ftill lower on the ft of January, in the following year, it had risen one-twelfth of an inch. The thermometer was conftructed by Mariotte; but unfortunately the space left by its falling, is not mentioned. Another thermometer was carried in October 1741, by M. Michely, into thefe caverns, and the fame thermometer in January, 1776, fell half a degree below the former mark: this was a month of very fevere cold. In another inftance, the thermometer varied at different times of a degree; but the heat, obferved in the fummer of 1775,

was

was the fame as was obferved in this cavern in the coldest seafon of the very fevere winter which followed. With thefe obfervations before him, M. Caffini began a new feries of experi ments, affifted by a thermometer of particular delicacy, conftructed by M. Lavoifier: each degree of a common thermo'meter occupied 4 inches 3 lines of this new inftrument, ftyled the thermometer of temperature.' It was carried, with the minutest precautions, into the cave, and the series of obfervations is fubjoined: we fhall transcribe the results in the words of our author, a little fhortened.

1. The abfolute temperature of the caverns of the obferva. tory, in the beginning of August, 1783, according to my new thermometers (graduated according to Fahrenheit's fcale), appears to be 9., or more accurately, 9.09. The greatest heat of that month, in the open air, was 20°. This is nearly the fame as M. Gentil obferved during the fummer of 1775, for we faw before, that with a thermometer of M. de la Fond, he found the heat to be 91*.

2. In the last days of January 1784, the thermometer, exposed to the open air, fell 20° below froit. My thermometer of temperature was only at 9.012, that is, there was only about 0.03 difference, though in the open air the difference amounted to 30°.

3. In the 5 lafst days of May, which were the hottest of the year 1784, the external thermometers arofe to 21°, and the temperature of the caverns returned to 9.09, the point obferved in August 1783, which gives a diminution of 0.03 in the height of the mercury in the caverns, while in the open air it had arifen 31. But, in the last article, the mercury in the cavern was found to have rifen 0.03, while the mercury in the open air had funk 30o.

6 4. The variation of the mercury, in the intermediate periods, had been more confiderable. At the end of August 1783, it was at 9.05 in the caverns; at the end of October 9.011; on the 211t of December 9,0124: to decide therefore on the variation of the temperature it is neceffary to obferve, not only on the hottest and coldest days.

Surprifed, faid M. Catlini, to fee the mercury in the thermometer of temperature rife, when in the other thermometer it funk, before my period of obfervation ended (from August 1783 to July 1784), I paid a particular attention to this phenomenon, and continuing after that time my obfervations, I faw it daily confirmed. In fact, in the months of June and July, 1784, which were the leaft warm, my thermometer, in the cave, rofe to 9.014. Autumn came, and it continued to afcend, even with a more rapid and more progreffive pace than

• We have not reduced these numbers, fince the differences are so mi. nute it is enough to obferve, that a degree of Reaumur's thermometer quals two one-fourth of Fahrenheit.

in