795

Essay IV. On Caloric.

796

cessive heats of the torrid zone, whilst | placed it in the focus of one of the

it diminishes the excessive cold of the polar regions.

Radiation of Caloric.

Herschel, in his experiments upon the solar ray, found that the different coloured rays have different heating powers: the most refrangible of the visible rays, the violet, is least powerful in exciting heat; and the calorific power increases towards the other side of the spectrum, and is greatest in the red rays. He found also that calorific rays exist apart from the rays of light, and beyond that side of the visible prismatic spectrum bounded by the red rays; the maximum of heating power being traced to the extent of even an inch and a half beyond the visible rays of light. This proves the existence of radiant caloric in the solar beam. It appears, from experiments which have been made by different chemists, that blackened surfaces radiate most, and that the worst radiaters are polished surfaces: the radiating power therefore is inversely as the reflecting power.

mirrors; the other mirror was placed at the distance of 10 feet 6 inches, and in its focus was suspended a small When bodies are heated to a high mercurial thermometer having Fahtemperature, caloric is emitted from renheit's scale. This in two minutes them in straight lines, moving with rose from 47 degrees to 50: and great velocity, and obeying the same when the vessel was removed, it belaws as the rays of light. This is gan to fall. These experiments sufwhat is called the radiation of caloric. ficiently prove that heated bodies raLambert found that from burning char- | diate caloric, and that this effect is coal, placed between two concave not owing to the emission of light, mirrors, such a heat was produced as but of calorific rays. to burn a combustible body at the distance of 20 or 24 feet: in order to determine whether this arose from the light emitted, he collected in the focus of a large lens the light of a clear burning fire, but found it produced no heat sensible to the hand. Not only do bodies raised to a high temperature radiate caloric; when moderately heated, the same effect is produced. Saussure and Pictet procured two concave mirrors of tin, moderately polished, a foot in diameter, with a focus of 42inches. These were placed opposite to each other, at the distance of 12 feet 2 inches. In the focus of one of them was the bulk of a mercurial thermometer; in that of the other was put a ball of iron 2 inches in diameter, which had been raised to a red heat, and allowed to cool until it was no longer luminous in the dark. The moment the ball was introduced, the thermometer in the opposite focus began to rise, and The Florentine academicians made in six minutes it had risen from 4 de- an experiment which seemed to prove grees to 14 of Reaumur's scale; while the radiation of cold; they relate their another thermometer, suspended with- experiment in the following manner. out the focus, but at the same dis-"We were desirous to try whether tance from the heated ball, rose only a concave speculum, exposed to a from 4 degrees to 6. This proves mass of ice weighing 500 pounds, therefore, that bodies at low tempera- would reflect any sensible cold on a tures emit caloric in straight lines, very delicate thermometer of 400 deand that the quantity emitted is suffi- grees, placed in its focus. The recient to produce a considerable ele- sult was, that the thermometer invation of temperature. It is evident stantly sunk but a doubt remained that the calorific rays are thrown upon whether the thermometer was acted the focus of the mirror placed oppo- on more by the direct cold of the ice, site to the heated body, and that these or that reflected by the speculum. are again reflected upon the thermo- This doubt was removed by covering meter within the focus: whilst the ther- the speculum; and certain it is, (whatmometerwithout the focus received only soever might be the cause,) that the a few direct rays from the surface of spirit began to rise again. the ball. Pictet performed another experiment, in which the operation of light could not be suspected. He filled a glass vessel, capable of containing rather more than two ounces by measure, with boiling water, and

Pictet and Mr. Leslie have made experiments upon this subject, and have obtained similar results. In these experiments we have therefore an apparent frigorific principle. It is supposed, however, that the apparent

797

Caloric. History of the Potato.

798

universally acknowledged, by the extensive cultivation which it has obtained. Its introduction, however, was at first much opposed, through some of those unaccountable prejudices which occasionally diversify and degrade the human character.

According to general opinion, this esculent root was first brought into England from Virginia by the much celebrated, but ill-fated Sir Walter Raleigh, who, on his return homeward in the year 1623, stopping at Ireland, distributed a great number of potatoes in that kingdom. These having been planted, multiplied so exceedingly, that in a comparatively short time their cultivation became general; and it is well known, that for a number of years past, potatoes, among the peasantry, have held a primary rank among the necessaries of life.

diminution of temperature which is observed, is not owing to the radiation of cold, but to the radiation of caloric from the thermometer which is placed in the focus of the speculum; the thermometer being to the cold body what the ball of iron is to the thermometer, in the experiment which we have before related. Prevost gives the following explanation of this sub- | ject. “When a body is placed in the focus of the mirror A, whose temperature is superior to that of the thermometer in the focus of the opposite mirror B, though the ball of the thermometer is radiating caloric, yet the hot body opposed to it, giving out more caloric in the same mode, and this being reflected on it by the mirror, the temperature must rise. When both the substance made the subject of experiment and the thermometer, are at the same temperature, neither suffers any change, because the quantity emitted from each being the same, and the reflection and condensation by the mirrors being alike, each receives as much as it gives out. But when the temperature of the body placed before the mirror A, is inferior to that in the focus of the mirror B, though it is still radiating caloric, the quantity is inferior to what the thermometer radiates: the latter therefore receives less than it gives, and therefore must fall." This certainly appears to be the more probable manner of accounting for this circumstance, since no proof, independent of a mistaken explanation of these experiments, has been adduced in favour of the actual existence of a fri-rous experiments have been tried gorific principle. Besides, it has been to find the best ways of improving found that bodies reduced to a lower the cultivation of this valuable article, temperature than that of ice, upon the and great success has crowned many application of a body whose tempera- efforts. Within this period, the culture was still further reduced, have ture of potatoes has taken a very geemitted caloric. It is therefore difficult neral spread throughout every part to conceive of bodies emitting caloric of England, particularly in Lancaand cold at the same temperature. shire, Cheshire, and Cornwall; and in Scotland they are cultivated even more than in this country. On their ON THE HISTORY OF value, it is needless to expatiate. Mr.

OBSERVATIONS

THE POTATO.

THERE is no root of which we have any knowledge, equal in value to the Potato; and scarcely one with the natural history of which we are less acquainted. The discovery of this valuable root has been of the utmost importance to mankind. This is now

From Ireland they were brought into England; and, owing to a ship loaded with potatoes being wrecked on the coasts of Lancashire, their cultivation in a field was first generally established in that county. By this incident, the Lancashire farmers have obtained a name for the cultivation of potatoes, which no other county in England can rival; and, what is of more importance, they have justly merited the celebrated character which they have obtained. In no part of this kingdom have potatoes been cultivated with superior success. soil seems to be congenial to their nature; and, for flavour and excellence, they have never been surpassed.

The

During the last fifty years, nume

Donaldson has justly said, that they may with the utmost propriety be denominated the "bread-root" of Great Britain and Ireland.

But although common opinion seems to have assigned to Sir Walter Raleigh the honour of having first introduced this valuable root into these kingdoms presumptive evidence has been a

799

Observations on the History of the Potato.

ced to render his claims somewhat doubtful. Several kinds of potato have, at various times, made their appearance in England; and it is not improbable that these may have been imported by different persons, whose names may have been confounded, while the peculiarities of the root which they severally imported may have lost their discriminations, and have obtained different associations. It seems, however, to be uniformly admitted, that the potato was originally a native of America; since, prior to the discovery of that vast continent, its existence in Europe was wholly unknown; and all our accounts, how much soever they differ from one another in other respects, invariably carry us across the Atlantic for the origin of this valuable root.

800

The said Thomas Herriot, who was probably sent out, as it is said, to examine the country, and to report to those who employed him the nature and produce of the soil, wrote an account of them, which is printed in the first volume of De Bry's Collection of Voyages. In this account, under the article of Roots, in page 17, he describes a plant which is called Opanawk. "These roots are," he says, round, some as large as a walnut, others much larger; they grow in damp soils, many hanging together, as if fixed in ropes: they are good food, either boiled or roasted."

66

Gerarde, in his Herbal, published in the year 1597, gives a figure of the potato under the name of the Potato of Virginia, and asserts that he received the roots from Virginia, which are otherwise denominated Norembega. The manuscript minutes of the Royal Society, 13th of December, 1693, assure us, that Sir Robert Southwell, then president, informed the fellows at a meeting, that his grandfather brought potatoes into Ireland, having first had them of Sir Walter Raleigh.

It was lately stated in an American paper, that Dr. Baldwin, surgeon of the frigate Congress, has decided the much-controverted question relating to the native country of the potato. He says, that he found this valuable vegetable growing abundantlyon the north side of the Rio de la Plata, in wild and uncultivated situations, and also among the rocks of Monte Video. He likewise This evidence, it is supposed by Sir adds, that its use was totally unknown Joseph, proves, in no very satisfacto the inhabitants of these regions. tory manner, that the potato was first In the first volume of the Transac-brought into England, either in the tions of the Horticultural Society of London, the late Sir Joseph Banks has given the following curious and interesting account of the introduction of this species of Solanum, or the common potato, into this country, and Europe. The notes from which this account has been principally taken, have, it is said, been some of them collected from authorities of difficult access, by the learned and very intelligent Mr. Dryander.

It is stated, he observes, that the potato now in use, was brought into England by the colonists sent out by Sir Walter Raleigh, "under the authority of his patent, granted by Queen Elizabeth, for discovering and planting new countries not possessed by Christians," which passed the great seal in 1584. Some of Sir Walter's ships sailed the same year; others, on board of which was Thomas Herriot, afterwards known as a mathematician, in 1585; the whole of them, however, returned, and probably brought with them the potato, on the 27th of July,

1586.

year 1586, or very soon after that period, and sent from thence to Ireland, without delay, by Sir Robert Southwell's ancestor, where it was cultivated and cherished for food before the people of England knew its value; for Gerarde, who had this plant in his garden in 1597, recommends the roots to be eaten as a delicate dish, not as common food.

It appears, however, he says, that it first came into Europe at an earlier period, and by a different channel; for Clusius, who at that time resided at Vienna, first received the potato in 1598, from the governor of Mons in Hainault, who had procured it the year before from one of the attendants of the pope's legate, under the name of Taratonfli, and learned from him, that in Italy, where it was then in use, no one certainly knew whether it originally came from Spain or America. But whatever the Italians may assert, it is not to be conceived, had it been of European origin, that its native country would have remained so long

unknown.

801

History of the Potato.-Sepulchral Bones.

Peter Cicca, in his Chronicle, which was printed in 1553, tells us, it is said, in chap. XL. p. 49, that the inhabitants of Quito, and its vicinity, have a tuberous root which they eat, called papas; this, Clusius guesses to be the same sort of plant he received from Flanders: and this conjecture has, it is said, been confirmed by the accounts of travellers, who have since that period visited the country.

It is concluded, that, from these details, it may fairly be inferred, that potatoes were brought into Europe from the mountainous parts of South America, in the neighbourhood of Quito; and that, as the Spaniards were the sole possessors of that country, there can be little doubt of their having been carried first into Spain; but that, as it would take some time to introduce them into use in that country, and afterwards to make the Italians so well acquainted with them as to give them a name, there is every reason to believe that they were in Europe before they were sent to Clusius.

SEPULCHRAL BONES.

MR. EDITOR.

802

Respected Sir,-Passing lately through Northamptonshire, I was invited to accompany a friend in a visit to the church at Rowell, a village on the road betwixt Market Harbro' and Kettering, distant from the former 7 miles, and from the latter 4. The church, from its curiously carved seats, &c. its places for holy water, and what is there called a stone pulpit, bears evident marks of great antiquity, and of Popish dominion. But what most arrested my attention, was a spacious vault under the west end.

Attracted by this, a venerable keeper, myself, and friend, each being furnished with a lighted candle, descended by a winding staircase to a considerable depth; where, to my astonishment, I soon found myself surrounded with an astonishing pile or wall of human sculls, and other bones. The vault I thought to be about ten yards long, and from four to five broad; and the pile of sculls, As the name of the root in South extending all round, except at the America is papas, and in Virginia that small door by which we entered, was of opanawk, the name of potato was, in some places nearly two yards high, it is said, evidently applied to it on and from one to two in breadth. account of its similarity in appearance strikingly exact and imposing manner to the battata, or sweet potato; and in which they were all arranged, toour potato appears to have been dis-gether with the equal state of presertinguished from that root by the ap-vation_they all seemed to be in, as pellation of Potato of Virginia, until the year 1640, if not longer.

It is added, that some authors have asserted, that potatoes were first discovered by Sir Francis Drake in the South Seas; and others, that they were introduced into England by Sir John Hawkins: but in both instances the plant alluded to is said to be clearly the sweet potato, which was used in England, as a delicacy, long before the introduction of our potatoes; it was imported, it is said, in considerable quantities, from Spain and the Canaries, and was supposed to have possessed the power of restoring decayed vigour.

The

far as I could examine them, led me to conclude that the solemn pile had been the work of some one given time, and of the same individuals; and the more especially so, as, upon inquiry, I was informed, that though there were various documents, in the church books for several hundred years back, yet there was nothing respecting them; and that no one could be found, who knew any thing, either when, or by whom, they were placed there. The only conjectures in the village were, that there had been some desolating disease, or some great battle fought near that place, and that they had been collected and preserved at that It is also further noticed, that the time. The latter conjecture appeared potatoes themselves were sold by iti- to obtain most credit with the people. nerant dealers, chiefly in the neigh-As to the number, I could not form bourhood of the Royal Exchange, and any tolerably correct idea, but it purchased at no inconsiderable cost must be very great. by those who had faith in their alleged properties. The allusions to this opinion are, it is observed, very frequent in the plays of that age.

On entering the vault, a thinking mind is almost irresistibly led forward to the awful scene which the morning of the resurrection will probably pre

sent to our astonished view. Whether ever the pious Hervey visited this instructive scene or not, I cannot tell, but I should think it highly calculated to put in motion the mind and pen of such a rich and contemplative genius. Could any of your numerous readers, who are acquainted with the ancient and topographical history of that neighbourhood, throw any light upon the time, cause, &c. of this "place of sculls and valley of dry bones," they would oblige, respected sir, yours truly,

present day. War has happily disappeared, and the nation at present enjoys both foreign and domestic peace. He who succeeds in prospering the state in respect of its government, is certainly worthy of the greatest commendation. And, when comparing the merit of a skilful legislator, with that of a skilful general, I should

determine

Cedant arma toga, concedat laurea linguæ. "There are," says Bacon, "counsellors and governors which may be held sufficient, negotiis pares, able to ma