But if one escape from within, it comes with a very different Not so when temper, and appears commissioned to avenge public wrongs, sent out to apparently and prepared to sacrifice its life in the execution of its orders. fight. I discovered the circumstance, that wasps thus excluded from their nest would neither defend it nor themselves, at a very early period of my life; and I profited so often, by the discovery, as a schoolboy, that I am quite certain of the fact I state; and I do not entertain any doubt, though I speak from experiments less accurately made, that the actions of bees, under similar circumstances, would be the same®.

supposing bees wax an animal

substance.

Mr. Hunter conceived bees wax to be an animal substance, Mr. Hunter mistaken in which exuded between the scales of the belly of the insect; but I am strongly disposed to believe, that it is collected from plants, and merely deposited between the scales of the belly of the bee, for the joint purposes of being carried with cônvenience, and giving it the temperature necessary for being moulded into combs: and I am led to this conclusion, not only by the circumstance of wax being found in the vegetable world, but also by having often observed bees employed in detaching something from the bases of the leaves of plants with their forceps, which they did not deposit on their thighs, * A curious circumstance, relative to wasps, attracted the notice of Abundance of female wasps some of my fiends last year, and has not, I believe, been satisfactorily accounted for A greater number of female wasps were observed in different parts of the kingdom, in the spring and early part of the summer of that year, than at almost any former period; yet scarcely any nests, or labouring wasps, were seen in the following autumn; the cause of which I believe I can explain. Attending to some peach trees in my garden, late in the autumn of the year 1805, on which I had been mak ing experiments, I noticed, during many successive days, a vast number of female wasps, which appeared to have been attracted there by the shelter and warmth of a south wall; but I did not observe any males. At length, during a warm gleam in the middle of one of the days, a single male appeared, and selected a female close to me; and this was the only male I saw in that season. The male wasp, which is readily

distinguishable from the female and labourer, by his long antennæ and

in 1786.

shining wings, and by a blacker and more slender body, is rarely seen out This accounted for. of the nest, except in very warm days, like the drone bee; and the nests of wasps, though very abundant in the year 1805, were not formed till remarkably late in the season; and thence I conclude, that the males had not acquired maturity till the weather had ceased to be warm, and that the females, in consequence, retired to their long winter sleep without having had any intercourse with them.

VOL. XIX-APRIL, 1809.

as they do (I believe invariably) the farina of plants. I have also frequently observed the combs of very late swarms to be remarkably thin, and white, and brittle; which are circumstances very favourable to the conclusion, that the wax is a vegetable substance, for it would probably be less abundant during autumn than in summer; and that portion which had remained on the plants till late in the season would hence become more colourless by exposure to light, as well as more dry and brittle than when it first exuded; but were it an animal substance, there does not appear any reason, why it should be more dry and brittle, or less abundant, in the autumn, than in the spring and summer. The conclusions of Mr. Hunter are, however, always drawn with so much caution, and he united so much skill and science with the greatest degree of industry, that it is not without much hesitation and diffidence, that I venture to put my opinion in opposition to his authority.

Elton, May 4, 1807.

T, A. KNIGHT.

Description of

a mercurial

pendulum.

III.

Description of a Mercurial Pendulum. Communicated by Mr.
BARRAUD, of Cornhill, who has made several, and has been
highly satisfied with their performance in the Measure of
Time.

THE whole length of the pendulum rod, from the rivet

that joins the spring to its top, to the end of the screw at L, fig. 1, Pl. VII, is 33 inches, (say 34 inches). The side pieces of the frame M M are of steel, as thick as the rod, that is of an inch, and not less. The top of the frame H consists of two pieces of steel, each of an inch thick, shaped as in the drawing, and screwed over the ends of the side pieces M M. The inside height of the frame, from E to A, is 8 inches, and the inside width between the pieces M M about 2 inches, so that the cylinder stands † of an inch clear of them. The bottom piece N is an inch thick

from

1

1

from E to R, and hollowed down to of an inch, so as to fit Description of / the bottom of the cylinder.

L is the bottom of the rod, and one inch of the end of it is made into a screw, that has forty threads in an inch. The nut K is of an inch deep, and the diameter of its circle from m to n is 1 inch, having the upper edge divided into 28 equal parts, and figured 0, 1, 2, 3, or at each 7th division. Each of these divisions is very nearly equal to 1′′ in 24 hours.

The quantity of quicksilver required is between 10 and 11 lbs. It should fill the glass cylinder up to P, being 6'4 inches from the bottom of the glass, measured internally. Fig. 2 is the cover of the glass cylinder, and fig. 3 the bottom of the frame, that supports the cylinder, both viewed vertically.

If with this pendulum the clock be found to go right with the thermometer at 30°, and loses 1" in 24 hours with the thermometer at 90°, it will be remedied by adding 10 oz. of quicksilver; and if the reverse by taking out that quantity.

The rod should be of an inch thick, and of an inch wide. The spring should be an inch long, and pretty stiff.

a mercurial pendulum.

IV.

Observations on the Nature of the new celestial Body discovered by Dr. OLBERS, and of the Comet which was expected to appear last January in its return from the Sun. By WILLIAM HERSCHEL, L. L. D. F. R. S.*

THE late discovery of an additional body belonging to the Account of

the new planet received April

solar system by Dr. Olbers having been communicated to me the 20th of April, an event of such consequence engaged my 20th, 1807. immediate attention. In the evening of the same day I tried to discover its situation by the information I had obtained of its motion; but the brightness of the moon, which was near the full, and at no great distance from the object for which I looked, would not permit a star of even the 5th magnitude to be seen; and it was not till the 24th, that a tolerable view