then brufhing, or laying on more amalgama, holding the piece al moft uuder his nofe; and as a fmall degree of heat raifes mercury into fumes, it readily occurs, that the heat of the metal forms that noxious vapour which he receives into his lungs every time he breathes, unless it be diverted by fome current of air; and then its baneful effect may in a lefs degree fpread in the room, ftill be felt by him and those who are obliged to be with him. To remove all that mifchief, the inventor has thought of collecting the noxious vapour together, and conveying it directly up into the chimney. To do this he has contrived a funnel fixed against the breaft of the chimney, over the fpot where the work is held during the operation, and from which the fumes muft rife into it. This funnel, or receiver, as he calls it, is, as to fhape, like a common, wide, fatted, tin tube, with a joint or return in the upper part, carried through the brick work into the flue, as a channel of conveyance into the chimney; but the afcent of the vapour being flow and uncertain, without a draught of air to lead it up, he hath further contrived a tin pipe, one end of which is fixed in the lower part of the funnel, and the other in the valve or draught-hole of a large fized bellows, refting upon the upper part or returning joint of the funnel, and having its nozle led (over the funnel) through the brick-work into the flue. The effect of these bellows is to draw up and force the floating fumes into the chimney; and that is obtained by the operator's working them with his foot, by means

--

of a line faftened to the upper handle of the bellows, and carried over a pulley fkrewed into the ceiling, or into a piece of wood projecting from the chimney, and thence brought down and tied to a ftirrup, with which it is moved up and down like a treadle.Another part of the invention is a glazed frame or window-fafh, placed between the operator and his work, to fkreen him from the approach of the noxious fumes; it is either ftraight, and of the breadth of the chimney, without a return, and made to flide up and down; or elfe, as he fays, for large work made circular, and of a fize to compass the funnel, and close against the corners of the chimney; and then, inftead of a fliding part, to have in front two of the fquares not glazed, but lined with leather fleeves for the arms to pafs through to the work; which by either of thofe modes of prevention, he affures, may be done without hurt to the health of the operator.

The fubiect of the memorial, and the invention disclosed by the model, being taken into confideration, the Society refolved, That a

machine of a proper fize for a common chimney fhould be conftructed at their expence; and Mr. Platts, a workman in the watergilding way, being found willing to make the trial, the machine was put up in his room; and a day being fixed, feveral members of the Society went to fee its ef fect, and reported, that they had not felt any of the (fo called) sweet vapour during the operation; after which the following letter was received by the secretary:

Sir,

To Mr. More.

HAVING been informed it was neceffary that I fhould deliver my opinion of the machine for preventing the ill effects of mercury in water-gilding, I have the pleafure to inform you, that I have made ufe of it ever fince the trial, and wish I had been fo happy as to have had the ufe of fuch an invention twenty years ago: I make no doubt but I fhould have been free from the diforder I have fo long laboured under. As the gentlemen have been fo indulgent as to favour me with the opportu-, nity of experiencing thefe falutary effects, I fhall from gratitude be ready to inform every perfon of the conftruction of the machine, as far as lies in my power. I am, Sir,

your humble fervant,

M. PLATTS.

Upon the confirmed report, and the additional circumftances of cheapness and fimplicity of conftruction, recommended in the advertifement for the prefervation of the health of poor workmen, it was refolved, That the candidate, Mr. J. Hills, was justly entitled to the premium, being twenty guineas, offered for difcovering to the Society an effectual method of preventing the ill effects in watergilding filver, copper, or other metals.

N. B. Mr. Hills, originally a feal-engraver, fince moved to No. 82, Berwick-ftreet, Soho, keeps a fhop of natural and artificial curiofities; and of glass Stained by his particular invention.

Account of the Ufefulness of Wash ing the Stems of Trees. By Mr. Robert Marham, Stratton, F. R. S. From the Philofophical Tranfactions, vol. lxxi. part 2.

1

THE following account is a kind of poftfcript to my letter to Dr. Mofs, Lord Bishop of Bath and Wells, in 1775, which the Royal Society did me the honour to publish in the Philofophical Tranfactions in 1777. In that I fhewed how.much a beech increafed, upon its ftem being cleaned and washed; and in this I fhall fhew, that the benefit of cleaning the ftem continues feveral years; for the beech which I washed in 1775 has increased in the five years fince the washing, eight inches and fix-tenths, or above an inch and seven-tenths yearly; and the aggregate of nine unwashed beeches of the fame age does not amount to one inch and threetenths yearly to each tree. In 1776 I washed another beech (of the fame age, viz. feed in 1741); and the increase of four years fince the washing is nine inches and two-tenths, or two inches and three-tenths yearly, when the aggregate of nine unwashed beeches amounted to but one inch and three-tenths and a half. In 1776 I washed an oak which I planted in 1720, which has increased in the four years fince washing seven inches and two-tenths; and the aggregate of three oaks planted the fame year (viz. all I meafured) amounted to but one inch yearly to each tree. In 1779 I washed another beech of the fame age, and the increase in 1780 was

three

three inches, when the aggregate of fifteen unwashed beeches was not full fifteen inches and fixtenths, or not one inch and half a tenth to each tree; yet most of of these trees grew on better land than that which was washed. But I apprehend the whole of the extraordinary increase in the two last experiments fhould not be attributed to washing; for in the autumn of 1778 I had greafy pondmud fpread round fome favourite trees, as far as I fuppofed their roots extended; and although fome trees did not fhow to have received any benefit from the mud, yet others did; that is, an oak increafed half an inch, and a beech three-tenths above their ordinary growth. Now though the beech gained but three-tenths, yet, perhaps, that may not be enough to allow for the mud; for the fummer of 1779 was the most ungenial to the growth of trees of any fince I have measured them; fome not gaining half their ordinary growth, and the aggregate increafe of all the unwashed and unmudded trees that I measured (ninety-three in number of various kinds) was in 1779 but fix feet five inches and feven-tenths, or feventy-feven inches and feven-tenths, which gives but eight-tenths and about one-third to each tree; when in 1778 (a very dry fummer in Norfolk) they increased feven feet and nine-tenths, or near eignty-five inches, which gives above ninetenths to each tree: and this fummer of 1780, being alfo very dry,

yet the aggregate increase was a bove half an inch more than in 1778. But the beft increase of thefe three years is low, as there are but twenty of the ninety-three trees that were not planted by me, and greater increase is reasonably expected in young than old trees; yet I have an oak, now two hundred years old * (1780) which is fixteen feet and five inches in cir cumference, or one hundred and ninety-feven inches in two hundred years. But this oak cannot properly be called old. The annual increafe of very old trees is hardly measurable with a string, as the flighteft change of the air will affect the ftring more than a year's growth. The largest trees that I have measured are fo far from me, that I have had no opportunity of measuring them a fecond time, except the oak near the honourable Mr. Legge's Lodge in Holt Foreft, which does not flew to be hollow. In 1759 I found it was, at seven feet (for a large fwelling rendered it unfair to measure at five or fix feet) a trifle above thirty-four feet in circumference; and in 1778 I found it had not increased above half an inch in nineteen years. This more entire remain of longevity merits fome regard from the lovers of trees, as well as the hollow oak at Cowthorpe in Yorkshire, which Dr. Hunter gives an account of in his edition of Evelyn's Silva, and calls it forty-eight feet round at three feet. I did not measure it fo low; but in 1768 I found it, at

fort

four feet, forty feet and fix inchs; and at five feet, thirty-fix feet and fix inches; and at fix feet, thirty-two feet and one inch. Now, although this oak is larger near the earth than that in Hampfhire, yet it diminishes much more fuddenly in girt, viz. eight feet and five inches in two feet of height (I reckon by my own measures, as I took pains to be exact). Suppofe the diminution continues about this rate (for I did not meafure fo high) then at feven feet, it will be about twenty-eight in circumference, and the bottom fourteen feet contain fix hundred and eighty-fix feet round, or buyers 'meature, or feventeen ton and fix feet; and fourteen feet length of the Hampfhire oak is one thoufand and feven feet, or twenty-five ton and seven feet, that is, three hundred and twenty-one feet more than the Yorkshire oak, though that is fuppofed by many people the greatest oak in England.

I am unwilling to conclude this account of washing the stems of trees without obferving, that all the ingredients of vegetation united, which are received from the roots, ftem, branches, and leaves of a moffy and dirty tree, do not produce half the increafe that another gains whofe ftem is clean to the head only, and that not ten feet in height. Is it not clear that this greater fhare of nourishment cannot come from rain? for the dirty ften will retain the moisture longer than when clean; and

the nourishment drawn from the roots, and imbibed by the branches and leaves, must be the fame to both trees. Then must not the great fhare of vegetative ingredients be conveyed in dew? May not the mofs and dirt absorb the finest parts of the dew? and may they not act as a kind of fkreen, and deprive the tree of that fhare of air and fun which it requires? To develope this myfterious operation of nature would be an honour to the moft ingenious, and the plain fact may afford pleasure to the owners of young trees; for if their growth may be increased by cleaning their ftems once in five or fix years (and perhaps they will not require it fo often) if the increase is but half. an inch yearly above the ordinary growth, it will greatly overpay for the trouble, befides the pleafure of feeing the tree more flourifhing. Although the extra increafe of my first washed beech was but four-tenths of an inch, the fecond was nine-tenths and a half, and the third near two inches; fo the aggregate extra increase is above one inch and one-tenth yearly; and the increase of the oak is eight-tenths. But calling it only half an inch, then fix years will produce above five cubic feet of timber, as the oak is eight feet round, and above twenty feet long, and fixpence will pay for the washing; fo there remains nine. fhillings and fixpence clear gain in fix years.

Same Account of Lichfield, and its Cathedral. Extracted from Pennant's Journey from Chester to London,

L'

ICHFIELD is a place of Saxon origin, and owes its tife to Ceadda, or Chad, the great faint of Mercia. I omit the legend of the thousand Chriftians, difciples of St. Amphibolus, that were martyred here under Dioclefian; or the three kings flain at this place in battle, as fculptured over the town-hall. I take up its history about the year 656, when Ofway, king of the country, eftablifhed a bishopric here, and made Dwina, or Dinma, the first prelate. To him fucceeded Cellach and Trumber&t; and on his demife, the famous Ceadda. This pious man at firft led an eremitical life, in a cell, at the place on which now ftands the church of his name, and fupported himfelf by the milk of a white hind. In this place he was discovered by Rufine, the fon of Wolphere, who was privately inftructed by him till the time of his martyrdom, before recited. Remorfe and confequential converfion feized the Pagan prince. As fome fpecies of expiation, he preferred the

apoftle to the vacant fee. He built himself a small house near the church, and, with feven or eight of his brethren, during the interval of preaching, read and prayed in private. On the approach of his death, flights of angels fang hymns over his cell. Miracles at his death confirmed the holinefs of his life. A lunatic, that by accident escaped from his keepers, lay a night on it, and in the morning was found restored to his fenfes. The very earth taken out of it, was an infallible remedy for all diforders incident to man or beaft*. Ceadda was of course canonized; a fhrine was erected in honour of him; great was the

concourfe of devotees: the place increafed and flou rifhed.

The hiftory of our cathedrals is, in its beginning, but the hiftory of fuperftition, mixed with fome truth and abundance of legend: humiliating proof of the weakness of the human mind yet all the fine arts of paft times, and all the magnificent works we now fo juftly admire, are owing to a fpecies of piety that every lover of the elegance of architecture must rejoice to have exifted.