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ancient records from copies of them that were got abroad, and probably the stardards at the same time. The congius was restored by weight, according to the Plebiscitum Silianum, as the inscription on it testifies. The quadrantal was too cumbersome a vessel for common use, to which the congius (like our gallon) was well adapted; so that Mr. R. does not see what other purpose it could serve, but to adjust the congius to its capacity, and the foot to its side: but here we see the congius adjusted by weight, and it is not very likely that a new quadrantal should be made for no other end but to adjust the foot by, when so many copies of the old standard were extant. Therefore it is not improbable that the standard of the foot was at this time restored, without any regard to its relation to the quadrantal.
But as to the difference between the foot derived from the congius, and that found from other authorities, Mr. R. further observes, that the correct adjustment of weights to measures is a very difficult matter, even in this age and in this kingdom, where workmanship is arrived at a high pitch of accuracy. And what errors rude workmanship is liable to, sufficiently appears from the weights Pætus and Villalpandus have given of the congius. Therefore he sees no reason to reject the testimonies of those authors, who say that the cubic foot contained a quadrantal of wine; and as little to believe that these two standards were ever truly adjusted to each other.
But had the original standard of the Roman foot been truly adjusted to the quadrantal, and continued invariable from the time of its first establishment, yet a false measure of it might at one time or other have got into common use at Rome, as well as a false measure of the French foot did at Paris; where in the year 1668 the mason's foot was found to exceed the foot of the Chatelet by of a Paris inch, which is above of a London inch: and the unaccountable negligence which appears in the Roman coinage, gives sufficient ground to suspect that they were not more accurate in their measures,
LXX. Description of a Metalline Thermometer. By Keane Fitzgerald, Esq. F. R. S. p. 823.
Mr. Boyle, the great promoter of experimental philosophy, made a thermometer on the principle of air, which to a certain degree of heat or cold, answered very minutely. Alcohol, or spirit of wine, has been more generally used; but has been found to lose in time much of its expanding quality; and also to be frozen by an intense degree of cold. Mercury, as not deemed subject to these inconveniencies, has therefore been allowed the most proper for the purpose.
Mr. Fahrenheit has since improved the mercurial thermometer to a great degree, and brought it to as much perfection as perhaps it will bear. He has remarked, that when the barometer shows a greater degree of pressure of the
atmosphere; the same liquor will receive 8 or 9° of heat more than when the barometer is at the lowest. But whether this proceeds entirely from the liquor's receiving a greater degree of heat by the pressure of the atmosphere may be a matter of some doubt; as it seems, by comparing the mercurial with other thermometers, to be affected in some measure by the pressure of the atmosphere in all degrees of heat and cold.
The making of metalline thermometers has been hinted at by many; particularly by Mr. Smeaton in his curious observations on the expansion of metals, who recommends zink or spelter as most capable of expansion, and fittest for the purpose. Mr. F. has endeavoured to make one on this principle, which he lays before the Society, with a description of its construction, and an account of the few observations he had been able to make on it.
The structure of this instrument is very intricate and delicate, and in use is hardly practicable. Mr. F. acknowledges, that since this instrument has been made, he found in the Phil. Trans., that Dr. Mortimer had in 1735 given the R. s. a description and drawing of an instrument he invented for the purpose; and that Mr. Johnson had also given a drawing of another, invented by Mr. Fothringham.
Mr. F. finds, by comparing this instrument with a Fahrenheit's and a spirit thermometer, that it keeps at a medium between both; not rising at first so quick as the mercury, and somewhat quicker than the spirit. On placing them together in the sun, when its heat became intense, it rose at last faster than the mercury, and not so fast as the spirit; and it continued to rise for some time after the others became stationary.
He tried the expansion of a few metal bars, from artificial freezing, with pounded ice, and water that it dissolved into; on which was poured half an ounce of spirit of tartar, in which Fahrenheit's thermometer descended to within one degree only of the freezing point: to boiling water, in which it rose to 211o, though the water did but scarcely boil, for want of a sufficient number of lamps. The barometer stood at 30 inches, and the natural heat of the weather at 60° of Fahrenheit.
A bar of spelter 2 feet long, marked by the minute index.
Note. Each division marks the 73840th part of an inch expansion per foot. Mercury cannot be useful in trying any degrees of heat above what makes it boil; and it appears by Dr. Hinsell's account of the experiments lately made at
Petersburg, that it may be frozen by extreme cold; which makes it unfit for ascertaining the extreme degrees of either.
LXXI. Of a Bird supposed to be bred between a Turkey and Pheasant.*
Mr. George Edwards, F. R. S. p. 833.
Mr. E. received this bird from Henry Seymer, Esq. of Handford, near Blandford, Dorsetshire, with his letter, dated April 9, 1760: wherein he says.—“ I have taken the first safe opportunity of sending the two birds. The large one I verily believe is an accidental cross, as we sportsmen term it, between a pheasant and turkey. When the bird was just killed, the skin round the eyes was of a pale red-lead colour, and the eyes like a turkey's. As I live near the wood where they were found, I took great pains to get another of them, but was never so lucky as to find one. There were 3 at first, all of which I believe are now destroyed."
The bird is of a middle size between a pheasant and a turkey-hen, and shaped pretty much like a turkey: the bill, legs, and feet, are black, and shaped like a turkey's; it has a broad space of bare skin round the eyes, which, when the bird was living, was of a pale red-lead colour; the eyes like those of a turkey; the head and half the neck is covered with very short feathers, of a whitish clay colour, with transverse dusky bars, though the throat and fore part of the neck are wholly of a light clay colour. These short feathers occupy the head and that part of the neck which is naturally void of feathers in turkeys. On the lower part of the neck, the breast, and belly, the feathers are much longer, and of a black colour, with a purple and changeable gloss. The thighs and legs on their fore-part a little below the knees are covered with feathers transversely barred with clay colour and black. The back, coverted feathers of the wings and tail, are of a mixed colour, in very fine transverse lines of brown and black, though some of the coverts of the wings and tail have larger transverse bars of the abovesaid colours; the greater quills are dusky or black, powdered with small claycoloured spots; the inner coverts of the wings have white tips, which hide their bottoms, that are dusky. He counted 16 feathers in the tail, the outer ones shorter by 2 inches than the middlemost; their colour is composed of brown and black, mixed transversely, like those on the back, though they are more dusky toward their tips; the very tips being of a bright brown: the outer borders of the side feathers of the tail are of a bay colour; the covert feathers beneath the tail are of an orange colour, crossed with black; about the vent the feathers are white with dusky spots. The whole upper side nearly resembles
This bird is mentioned by most modern ornitholigists; who appear to acquiesce in the account and figure of Edwards, and consider the bird as a hybrid production between the common pheasant and turkey,
that of a hen pheasant, but darker coloured. The feathers of the body are all double; that is, two distinct feathers proceeding from one stem; the outer large, and of a firm texture; the inner smaller, and altogether downy.
Whether this bird be produced from a turkey-hen and a cock-pheasant, or from a turkey-cock and hen-pheasant, no one knows. Mr. E. thinks it rather from a hen-turkey and cock-pheasant; because their disparity in size is not near so great, as between the turkey-cock and hen-pheasant. Though the supposition. that this bird is from an egg laid by a hen-turkey trodden by a cock-pheasant, is attended with a difficulty not easily reconciled; for it is not probable that a hen-turkey, a domestic fowl, should betake herself to the woods, and bring up her brood wild and unobserved; which is contrary to the habit of turkeys in our country, where they are not originally natives. Why these mixed generations so rarely happen, is because nature has fixed the inclination of every distinct species to the contrary sex of its own identical species, from which, in a wild and natural state, it will hardly ever stray. The reason of the mixtures that we meet with, contrary to the ordinary course of generation, may proceed from some hindrance of the male's meeting with his proper female, or female with male, at the seasons when they are by nature appointed to propagate their species, which rarely happens; for in a wild state of nature most animals are numerous, and at their breeding seasons easily meet with males or females of their own. species. Disappointments of what they naturally seek, and accidental meetings of different species, near of kin to each other, cause these unnatural conjunc tions, which produce uncommon mixed species of animals. He believes that two species widely different from each other, as water-fowl and land-birds, &c. cannot possibly conjoin, so as to produce a living mixed offspring. He had been informed, and believed it may be true, that a mixed species has been produced between our common poultry and partridges that harbour near farmyards.
LXXII. On a late Discovery of Asbestos in France. By Mr. Turberville Needham, F.R. S. p. 837.
A singular discovery has accidentally been made in one of the French provinces, of the nature of asbestos, or amianthus. The proprietor of a certain forge, on taking down his furnaces to repair them, found a great quantity of this substance at the bottom. It answered effectually all the common uses of the native amianthus, either manufactured into linen or paper. In short, on a progress in this inquiry, he finds that both this which he obtained from the forge, and the native asbestos, is nothing more as he terms it, than calcined iron deprived of the phlogistic; and that by uniting the phlogistic, either with this or the fossile amianthus, he can restore it at any time to its primitive state of iron.
Does not this, with the discovery of lava, pumice-stones, iron in a perfect state, and many other traces of fire observed in most of the mountains, particularly in all the great chains, and remarkably in all those under the equator, which are the highest on the globe, seem to indicate, that the dry land, with all its eminencies, was originally raised out of the waters, by the force of subterraneous fire?
LXXIII. On the Hot Baths of Vinadio, in the Province of Coni in Piedmont.
The warm baths, which have been so serviceable to the Chevalier Ossorio, run through the rocks, near the village Vinadio, in the province of Coni. The water is very clear, and so warm, one cannot bear the hand in it: the contents are sulphur diffused through it, and some salt almost like common salt. By evaporation, you get 5, sometimes 6 gr. from 1 lb. of water. Dr. B. sent a small quantity of the salt, gathered from the stones by which the water runs, before the rising of the sun, for in the day-time it is not found upon them, except in winter. Where these waters run, they deposit oily particles, which by degrees join together, and form a soft, spongeous, greenish-yellow substance, an inch almost in thickness, which is called muffa: this, when dry, is wrinkled, takes fire, crackles, and gives the smell of brimstone, and when entirely burnt, leaves a black ash behind. A piece of silver immersed in these waters in a few minutes became black. Their taste is neither salt nor acid, but disagreeable. The muffa left for 2 days in common water, swells 6 times thicker than it was, stinks, and throws up oily particles on the surface of the water. The salt does not ferment with acids. If you dissolve it in common water, and mix it with syrup of violets, it gives some appearance of a green colour: the same water poured on a solution of silver, it soon throws down a white sediment. Some say these waters contain nitre, and particles of other bodies; but this has not been demonstrated.
The disorder of the Chevalier Ossorio was, that he had lost the feeling of his fingers, had a weakness in his hands and legs, so that sometimes he could not walk in a straight line, but tottered from side to side. He could not extend his toes, and the soles of his feet seemed as if hard strings were drawn across them. He tried many medicines to no purpose; but is now perfectly free from the above complaints by the use of these warm baths. He bathed in the waters 40 times, when the stomach was empty, in a morning; and staid in them at first an hour, but lengthened the time gradually at last to a full hour. After each bathing he was dried with cloths, and put into a warm bed, where a plentiful sweat came on for about an hour; during which, the pulse beat like that in a high fever, but became quieter as the sweating abated. When the sweating was almost over, and the pulse quite regular, he was dried again with cloths, his