visible in the day-time. But this reasoning will not apply to the fixed stars; since no telescope is found to augment their apparent size, so as to make them resemble planetary disks. I am aware that it may be said, that the telescope excludes almost all the light except what comes from the object, and thereby prevents the impression made by its light from being effaced; and that by increasing the magnifying power the ground upon which it is seen becomes darker, forming a greater contrast to the light of the star. That the first of these considerations, however, is not sufficient to account for the effect, I am pretty much convinced by the following experiwent. I have frequently directed a long tube, blackened in the inside, and furnished with proper apertures to exclude the extraneous light, to a star, about san-set, when it was easily seen with a very small degree of magnifying power, but could never perceive it through the tube, though I was perfectly certain it was pointed directly to the star. This experiment has uniformly failed of success in detecting a star till it became visible to the naked eye. That the darkness of the ground on which a star is seen is not, of itself, suficient to account for the effect produced by magnifying power, is also evident from the following circumstance, viz. that by diminishing the aperture of the object glass we may produce as dark a ground as we please; but this contraction of aperture will not produce the effect of rendering á star visible if a small power be applied 3 nay, by diminishing the aperture beyond a certain limit, we prevent a star from being seen, which would otherwise be quite perceptible, I am therefore induced to conclude that some additional reasons must be assigned why magnifying power produces this effect. To ascertain these reasons is the object of this query.

For similar reasons, I should wish to be informed if the faet is established beyond all doubt that the stars are visible in the day-time from a deep well or pit. This fact is generally taken for granted, both by philosophers and 'by the vulgar, and has been asserted by many respectable writers, both ancient and modern; but none of those whose works I have perused assert that they themselves, or any of their learned friends, have witnessed this phenomenon. Otto Guericke, without questioning the fact, attempts to account for it in the following manner : “ It is," says he," because the light which proceeds from the stars is not overpowered by the rays of the sun, which are lost in the number of reflections which they must undergo in the pit, so that they can never reach the eye of a sp

spectator at the bottom of it. But for the same reason they ought to be visible through a long tube, where the rays of light are prevented from striking the inside, by the interposition of proper apertures, and more especially when such a tube is accurately directed to a particular star, which is contrary to many experiments I have made to ascertain this fact. Have any of your numerous philosophical readers, or their friends, seen the stars from a deep pit in the daytime? Are colliers, miners, or subterraneous surveyors, who are frequently in favourable situations for this purpose, known to have

occasionally observed them? If so, are small stars distinguishable in such situations? or is it a star of the first or second

when magnitude happens to pass near the zenith that such a phenomenon is perceived ?

Is it a fact, as has been related by some authors, that the celebrated astronomer Tycho Brahe had an observatory in a deep pit or dungeon, where he frequently sat and contemplated the stars in the day-time, as reflected from mirrors which were placed around him in different positions for this purpose ?

An answer to any of the above queries, if they be not deemed too unimportant for discussion in the Annals of Philosophy, will much oblige, Sir, yours, &c.

T. Dick, Methven, near Perth, April, 1815,

1

IX. On the Explanation of the Fructionary. Calculus.

(To Dr. Thomson.) SIR, The following ideas owe their origin to the valuable article of Professor Christison in your last number. Theits merit, is certainly only of the ordinary kind, yet their publication may perhaps.do some gooda

ill, with To facilitate the conception of the generation of fuxional quang tities, I conceive that if the line A D (see the Professor's figure) be considered as a cylinder, on which is rolled a sheet of papers divided into the two parallelograms, AF, CE, the former being coloured black, and the latter red; then, when the paper is unrolled, it will be easy for the student to comprehepd the generation of the rectangles, and also their constant ratio to each other, which (Euclid 1, 6,) is as A E to ED, or, in the Professor's example, as 5 to 1.970 ICAC ?!

Ons 9 al 2911d 10 931971 Again, if A C D E, in fig: 2, represent a piece of paper forming a parallelogram, as A D, and a triangle, as A B C, having a series of equidistant lines, as N ML, H G F, &c. &c. drawn parallel to CBD, and on which the respeetive proportions of CB to B D, of NM to M L'of H G to G F, &c. &c. are written, then if CD

G represent a cylinder on which the paper is rolled, commencing at C'D, it is manifest when the A E will be the of the parallelogram and triangle, part first visible, and as , of increase,' by the , at or position, will be shown in the easiest and most familiar manner. This simple rivance will

i conceive, illustrate completely the Professor's idea, as the generation of the quantities can be easier comprehended by this mode than by supposing them to be produced by the motion of a line. I perfectly agree with your learned Cor. respondentă that the first principles : regence and indeed

of somewhat more, may be attained hy very young persons; and it is will gulur,ibat a simple and elementary

, treatise adapted to their consingular

a

OSO, engine their tecidating the principles of those intimately connected with the most profound and interesting departments of human knowledge. estung depart

I am not, however, a friend for the introduction of motion into the conception of fuxional quantities, as I conceive it to be foreign to the inquiry. I would rather consider the differential calculus as an extension of the science of algebra.

erdt 101 211001200 Jogih dopustha Mavi 5. 1815.4 no pian hour GEORGE HARVEY.TU

01.19 weis

Your humble servant,
Plymouth, ,
DIO

RETHOX 2710 9911do
X. Milky Juice of Plants. 4.9239,
Dr. John has lately examined the milky juice of several European
plants. I conceive that a short account of the results which he
obtained will be acceptable to the readers of the Annals of Phi-
losophy.

1. Leontodon Taraxicum (Dentylion). in The juice of this plant is liquid, and milk-white. It has a sweetish and very bitter taste, with a certain degree of sharpness. Its smell is similar to that of the fresh plant. When exposed to the air, it speedily coagulates, and acquires a violet-brown colour. The coagulated sap being boiled in water, communicates to that liquid a brown colour and a bitter taste, and the property of reddening litmus paper. The undissolved portion is white and elastic, and similar to caoutchouc. · It becomes brown by exposure to the air. Alcohol acts but feebly on it, dissolving only a little resin. The caoutchouc'burns with a brilliant flame. The watery solution was precipitated by oxalic acid, nítrate of silver, nitrate of mercury, and nitrate of barytes. Hence the constituents of this plant aree Water.

A trace of gum ?rinten 1595.16 Caoutchouc.

An acid.

grati! - Bitter extractive.

Murjate, phosphate, and sul; A sweet substance ?

phate of limes' and, of an A trace of resia,

alkali. Oui Oui A stts 2. Lactuca Sativa (Lettuce): 10.0.6 * Thiş plant yields but little milky juice. According to John, its properties are the same as those of the leontodon taraxicum, and its constituents the

s He was not able

able to determine wbether it contained an uncombined acid. From the known soporific powers of the juice of lettuce, there is reason to believe that it contains a

that which exists in
ub.common

It would be worth while to examine whether the juice of the leontodon taraxicum contains the same principle, trdi Jub.ro

10 1011001111 .

ETT ''joob.100 543. Ficus Carica (Fig Tree). THE 31.01 270 The twigs and footstalks of this tree yield á milky juice, which

the same.

substance similar to that which

opium,

2 lits seit Bus 1150 speedily coagulates in the air, and becomes a transparent mass, having the consistence and lustre of wax. The fresh sap has a

Wolteras bitterish and astringent taste, but produces no change upon the solutions of iron. Water dissolves a small portion of the coagulated sap. Alcohol at a boiling temperature dissolves about a third of it; but the resinous substance thus dissolved precipitates again as the liquid cools. The undissolved portion possesses the properties of caoutchouc. Hence the constituents of this sap are as follows:

To Caoutchouc.

tedA trace of extractive, soluble in Resin, soluble only in boiling water, alcohol.

Salts. 4. Platinus Occidentalis (Plane-Tree). Ristis : The bark and wood of these trees when young contain a milky juice. This juice, according to John, contains the following con stituents :Water.

A very small quantity of gummy Resin, soluble in boiling alcohol matter 2!11 13111, Jil: only.

Phosphoric acid.f., 157 .915.01: Caoutchouc.

Salts.

1,199

*

XI. Account of a dreadful Accident at Heaton Main Callicry

a

near Newcastle, * This colliery is situated in the bed of coal called the high maip. It is of a considerable depth, about 110 fathoms, and the shaft is situated at the lower extremity of the mine. The shaft is divided by boarding all the way down, so that the same opening served for the up and down east shaft. The seam towards the rise had been formerly worked as a colliery, under the name of Heaton Banks, by shafts distinct from the present working, which shafts, when the colliery was given up, were covered over with boards and earth. In the course of time these old workings had become filled with

' water ; and the managers of the present colliery being well aware of the danger attending so large an accumulation of water, the workings were proceeded in with the utmost caution,

The mine was very much subject to what the colliers call the ** creep, which is a gradual filling up of the horizontal passages. It * had been eustomary for some time past to bore in various directions upon the lines the men were working, in order to ascertain whether any body of water lay concealed in the adjacent cavities. This precaution was about to be put in practice at nine o'clock on Wed

Hesday the 3d of May, but before that time had arrived, (between a three and four o'clock in the morning,) a dreadful rush of water came through the roof in the north-west part of the colliery, and continued to flow with such rapidity, that only 20 men and boys were enabled to make their escape. In a very short time, the This account is partly

water, closed up the lowet mouth of the shaft; and that night it

cube rose to the height of 24 fathomas.

Some faint hopes being there? tained that the men below would retire to the higher parts of the workings, which were said to be above the letel of the water m thed

w shaft, every exertion was used to open a communication with themy by the old working push which coverede ind choaked up the

. mouths of two old shafts, when deprived of the support of the water, fell in, dragging along with it some trees which had been planted roumd the spot. An old shaft, in front of Heatow Hall, has not, however, presented a like impediment, and consequently every exertion is using to open a communication by that way. They had uncovered the pit, anid reaehed the scaffolding dr Saturday the

ne 6th, which was five fathoms from the surface; and we understand their efforts are likely to be successful, if not prevented by an accumulation of inflammable air, with which the old workings appear to be filled. Ever since the accident, three large engines fone of 130 horše power) have been constantly employed in drawn ing the water from the pits at the rate of about 1200 gallons per minute, yet on Friday morning it was found to have attained the height of 31 fathoms up the shaft. In the evening, however, the water had decreased about three feet, and we understand has con tinued to decrease since that time; so that no doubt is now entera tained of the colliery being at some future period again set to work. We now come to state the extent of the calamity. Mr. Miller

the underviewer, who has left as wife and eight children), 32 work men, 42 bogs, and 37 horses, have perished; and 25 widows, with about 80 children, are left to bemoan the sudden death of their busbands and fathers. We (1393 9/1 784 ? 13,9 So za vas dva

or colock to 90 99* zabuu21109 - 26 on vario citi socioria dois antes content and you ona bih dod stiw isvis 6374VOO 37977 7D (avia 26W veiling at: biti omogyi Osa tomu ť sa Haird pagit ARTICLE XIII. *!ło s2000 sdt nI

walo ; 7913 31* % t's ***W 'ic il-34[New Patents. 09118 19gabant to

{KOULD found at its baba gorg.919w agridov 21. JOHN CARPENTETT, Truto: for'a knapsacks which preyents the 7 wet coming between it and the backs and a pouch in it

in front sugo aipended from the shoulder straps of said knapsacky 60,jas, to couná

teraet its weightot Jan. 20, 18:15.W 01941 119m in anii uit You 21 JEAN RAUDONT, Oxford-streets for certain improvements in - the construction of dioptrie telescopes. Jan. 201815. 10 JAMES MILLER, Liverpool , ford certain improvements in the a' construction of stills, furnaces, chimneys, and other apparatus

connected with the art of distillation. Jan. 28, 1815. no 27 ni Joan Wood, Manchester, clock-makers for certain improve'ments in machinery, used for preparing and spinning cotton-wool and various other articles. Feb. 1, 1815. JOSEPH TAYLOR and PETER TAYLOR, Manchester, machine

Peter

ai 0910

.