been accumulated, till they find their equilibrium. If we add to the above the many chemical experiments which receive an easy and elegant explanation from the supposed matter of heat, as employed in the works of Bergman and Lavoisier, I think we may reasonably allow of its existence as an element, occasionally combined with other bodies, and occasionally existing as a fluid, like the electric fluid gravitating amongst them, and that hence it may be propagated from the central fires of the earth to the whole mass, and contribute to preserve the mean heat of the earth, which in this country is about 48 degrees but variable from the greater or less effect of the sun's heat in different climates, so well explained in Mr. Kirwan's Treatise on the Temperature of different Latitudes. 1787, Elmsly. London. NOTE VIII.--MEMNON'S LYRE. _So to the sacred Sun in Memnon's fane Spontaneous concords quired the matin strain._ CANTO I. l. 183. The gigantic statue of Memnon in his temple at Thebes had a lyre in his hands, which many credible writers assure us, sounded when the rising sun shone upon it. Some philosophers have supposed that the sun's light possesses a mechanical impulse, and that the sounds abovementioned might be thence produced. Mr. Michell constructed a very tender horizontal balance, as related by Dr. Priestley in his history of light and colours, for this purpose, but some experiments with this balance which I saw made by the late Dr. Powel, who threw the focus of a large reflector on one extremity of it, were not conclusive either way, as the copper leaf of the balance approached in one experiment and receded in another. There are however methods by which either a rotative or alternating motion may be produced by very moderate degrees of heat. If a straight glass tube, such as are used for barometers, be suspended horizontally before a fire, like a roasting spit, it will revolve by intervals; for as glass is a bad conductor of heat the side next the fire becomes heated sooner than the opposite side, and the tube becomes bent into a bow with the external part of the curve towards the fire, this curve then falls down and produces a fourth part of a revolution of the glass tube, which thus revolves with intermediate pauses.