too much exficcation; the latter being, from their general structure and conftitution, made fit to bear, and live in, the water; the for mer, by their conftitution and forms, to breathe, and dwell, in the air.

But it may be asked, why eels and water fnakes are capable of living longer in the air than the other kinds of fish? this is an fwered, by confidering the providential care of the great creator for thefe and every one of his creatures: for, fince they were capable of loco-motion by their form, which they need not be if they were never to go on fhore, it feemed neceffary that they fhould be rendered capable of living a confiderable time on fhore, other wife their loco-motion would be in vain. How is this provided for? why in a moft convenient manner; for this order of fishes have their branchia well covered from the external drying air, and are also furnished with a flimy mucus, which hinders their becoming crifp and dry for many hours, and their very kins always emit a mucus liquor, which keeps them fupple and moist for a long time; where. as the branchia of other kinds of fish are much exposed to the air, and want the flimy matter to keep them moift. Now, if, when any of thefe is brought out of the water, it was laid in a veffel without water, he might be kept alive a confiderable time, by only keeping the gills and furface of the skin conftantly wet, even with

out any water to fwim in.

fifh kinds, which is of a middle nature between the phoca, and the real fishes of the fea, in one peculiar refpect. This is the clafs of the phocenæ, or porpuffes, of which there are feveral fpecies; and these have lungs, and there. fore are forced to come up to the furface to breathe at very short intervals; but, when brought on fhore, have no progreffive loco motion. So that, having lungs, they refemble the phocæ, and, in every other respect, the real fishes : of the fea.

Blafius, in his Anatome Animalium, page 288, gives an account of one of thefe taken and brought on fhore alive; the people let him lie, to fee how long he could live out of the water; and he continued alive only about feven or eight hours, and exhibited a kind of hiffing voice.

From what has been faid, it will, I hope, appear rational, that these are the only two orders that can properly be deduced from the clafs of amphibious animals; and that the genufes of either order are very few in the animal world.

A letter from James Parfons, M. D.

F. R. S. to the right honourable "the Earl of Morton, prefident of the Royal Society; on the double borns of the Rhinoceros.

My Lord,

WHEN I had the honour of

horn

.

horn to the members; I have therefore taken this firft occafion to entertain the prefent members with a fight of a noble fpecimen of the horns of an African rhinoceros, brought from the Cape of Good Hope, by my curious and worthy friend William Maguire, efquire, among many other curiofities; prefuming that few of the fociety have ever feen a pair of the like kind. But what renders this fubject the more particular, and worthy of observation, is, that by means of knowing there is a fpecies of this animal, having always a double horn upon the nose, in Africa, Martial's reading is fupported against the criticism of Bochart, who changed the true text of that poet, in an epigram upon the ftrength of this animal; for when Domitian ordered an exhibition of wild beafts, as it was the cuftom of feveral emperors, the poet fays: The rhinoceros tofs'd up a heavy bear with his double horn:

this difference, that these changed the euros for urfos, as imagining they were rather bears than bulls that were thrown up by this noble animal.

Our then worthy prefident Martin Folkes, efquire, had feen my account of this fubject, at the end of which I endeavoured, however prefumptuously, to defend Martial's reading against Bochart and the other eminent perfons mentioned; and defired I would let it be read and printed, which I very readily agreed to, as his request did me much honour.

Before my paper was printed Mr. Maittaire and Doctor Douglas died; and the learned Doctor Mead was the furviving critic, upon this line, of the three. Upon this occafion, therefore, I have a double pleafure; first, in amusing the prefent gentlemen with a moft curious fpecimen in natural hiftory; and, fecondly, in remembering in this place, the nice candor and generofity of Dr. Mead upon that fubject. For, about four

extulit urfum.

he received a prefent of feveral curious fhells, feeds, &c. and with them the bones of the face of a young rhinoceros, with two horns, in fitu, all entire, by a captain of an African trader, who brought them from Angola.

As foon as he faw the horns, he fent to invite me to breakfatt, and there, in company, ingenu. oufly gave up his paft opinion, and declared for Martial; and, indeed, I muft add to the praife of that great man, that, as I was happy in being frequently at his houfe, I was witnefs to many fuch inftances of the moft difinterefted

candour

candour and generofity, where any part of fcience was the topic, among his felect friends.

This anecdote I thought proper to mention upon the prefent occafion; nor can too much be faid to his honour, among all lovers of philofophical learning. I am Your lordship's

moft obedient fervant, James Parfons. P. S. The dimenfions are as follows: viz. The length of the anterior horn, meafuring with a ftring along the convex fore part, is zo inches; perpendicular height 18; circumference 214 at the bafe; the pofterior horn is in perpendicular height 19; circumference round the bafe 18; length of both bafes together upon the nafal bones 14 and the weight of both together is 14 pounds 10

which you was pleafed to take of my letter upon the late comet, did not make me more careful to obferve whatever I thought might tend to improve the knowledge of nature, which is a capital part of the laudable defign of the fociety.

Your lordship knows, that my fituation expofes me to every blast that blows, and affords a fair opportunity for meafuring the velocity of the wind (the force of which I am, fo often, obliged to feel). I have attempted to determine this by letting light downy feathers fly in the wind (the method, I underftand, ufed by the ingenious Dr. Derham); but cannot fay, in all the trials I have made (though I have let fifty of thefe feathers fly, one after the other, at a time) that I have ever feen above one, or two at moft, upon which I could have founded a calculation. The velocity of the wind near the earth is very unequal, upon account of the frequent interruptions it meets with from hills, trees, and houfes; and even in open plains; the furface of the earth, though much smoother than it commonly is, muft reflect and interrupt fuch a fluid as the air, and occafion great irregularity in the velocity of its current: this is the reafon, when a feather is let fly with the wind, why it feldom, if ever, defcribes a ftrait line, but moves fometimes in a kind of fpiral, now high, and then low, fometimes to the right, and then again to the left; and whe two feathers let fly at once, feldom, if ever, keep together, or defcribe fimilar lines.

But, at fome confiderable dif tance from the earth, the velocity of the wind feems to be regular and fteady: nothing can be more

G

uni

uniform than the velocity of a cloud in the sky appears to be, even in the greateft ftorm: it is like a fhip carried away infenfibly by a fmooth and gentle current, paffing over equal paces in equal times. This fuggefted the thought, that the motion of a cloud, or its fhadow over the furface of the earth, would be a much more proper measure of the velocity of the wind.

In the end of March 1763, I had as favourable an opportunity of putting this method into prac tice, as I could have wished for: the ftorm was exceeding high, and moved with vaft velocity; the fun was bright, the sky clear, except where it was fpotted with light floating clouds; I took my ftation in the north window of my dining room, near the clock, from which I had a free profpect of the fields; the fun was in the meridian, the wind due weft interfecting his rays at right angles; I waited until the fore-part of the fhadow of a cloud,

Feet

that was diftinct, and well defined, juft touched a fouth and north line, which I had marked upon the ground; at that inftant I began my reckoning, and followed the fhadow with my eye in its progrefs, counting feconds all the while by the clock, until I had reckoned up 15 feconds; then I obferved exactly where the aforefaid edge of the fhadow was.

This experiment I repeated ten times in half an hour, and seldom found the difference of a second, in the time which different clouds took to move over the fame space. On the 5th of May current, I repeated the trial four different times, the fun being also near the meridian, the wind in the weft, with light clouds floating in a clear fky as formerly; and found that the fhadows of different clouds took fome of them 44, and others 45 feconds, to pafs over the fame fpace which they had moved over in 15 feconds, in the former trials.

60

Which fpace is 62.9 English miles per hour, the velocity of the wind in March 1763.

One third of this (or 21 miles nearly) fhews the velocity of the wind on May the 6th, when it blew a fresh gale.

'This day, May 12, there was a fmall wefterly breeze, the velocity of which I meafured upon the fame line, the fun being 10 miautes past the meridian, and found

that the fhadow took 95 feconds to pafs over the above space, which gives the velocity of the wind at the rate of 9.9 English miles per hour.

Thus, by having feveral lines in different directions of a known length marked upon the ground, one may eafily (and with great accuracy, I imagine,) meafure the velocity of the wind. If a perfon was provided with an inftrument

for

for meafuring the force of the wind, it would perhaps be worth while to obferve whether, when the velocities of different winds were the fame, (or nearly fo) the forces of thefe winds did not vary with the feasons of the year, the points of the compafs from which the wind blows, and alfo with the different state of the barometer and thermometer, fince the momentum of the wind depends not only upon its velocity, but alfo upon its denfity.

From the end of March 1765, to the end of March laft, we, in this part of Scotland, had very little rain, and lefs fnow in proportion; our rivers were as low, through the winter, as they ufe to be in the middle of fummer; fprings failed in moft places, and brewers and maltfters were obliged, even in winter, to carry their water at a confiderable distance; I was much afraid there would not be moisture enough in the earth for the purpofes of vegetation, if this feafon fhould fet in as dry as the former, before we got a new fupply of rain. In the end of March laft, we had a fall of snow; and, as I did not remember to have ever read an account of fuch an experiment, I wished to be able to determine, to what quantity of rain this fall of fnow was equal.

The fnow had been falling from five o'clock the former evening, till ten o'clock the next day; about eleven o'clock I meafured the depth of the fnow, and found it to be 6.2 inches; then I took a ftone jug, holding about three English pints, and turned the mouth of it downwards upon the fnow measured, and where the ground below was fmooth and hard; and by this

means I took up all the fnow from top to bottom in the jug; this fnow I melted by the fide of a fire, and the 6.2 inches of fnow yielded fix tenths of an inch deep of water in the fame jug. After emptying the jug, I dried, and weighed it in a balance, and took up the fame quantity of fnow in it as before, weighed it again, and found the weight of the fnow taken up, and from this weight computed what quantity of water it fhould have produced, and found that it ought to have produced fix tenths of an inch and one twentieth of an inch more then I diffolved the fnow, and found that it yielded a quantity of water in the bottom of the jug, fix tenths of an inch deep, as in the former experiment. The difference of one tw ntieth of an inch in the depth of the water, betwixt the weight and the melting of the fnow, was probably owing to an exhalation from the jug, while the fnow was melting by the fire, for I obferved a fteam fometimes rifing from it. A great or leffer degree of cold, or of wind, while the fnow falls, and its lying a longer or fhorter while upon the ground, will occafion a difference in the weight and in the quantity of water produced from a certain number of cubic feet, or inches, of fnow; but, if I may truft to the above trials, (which I endeavoured to perform with care) fnow, newly fallen, with a moderate gale of wind, freezing cold, which was the cafe of the fnow I made the trials upon, the 27th of March last, will produce a quantity of water equal to one tenth part of its bulk; or the earth, when covered with fnow, ten inches deep, will