^{page 15 note *} See Edinburgh New Philosophical Journal for 1835.

^{page 18 note *} In constructing each valve, four folds of the leaf are employed. Should the valves become impaired by use, they may easily be renewed, and the leather of the piston may also in time require renewal also.

^{page 19 note *} Whilst revising the proof sheets of this paper in the month of June in London, I have had opportunities of trying the instrument at higher temperatures at an open window; and with the external thermometer at 68° have effected a reduction of 34½°, the dew point being on one occasion found to be 31½° below the temperature of the air.

^{page 21 note *} In support of the great trustworthiness of Dalton's method, I may appeal to the opinion of Professor James Forbes, 2d Report on Meteorology to British Association, 1832; and to Dr Thomson's opinion, there referred to. It is unnecessary to say that I had previously compared the thermometers, and that I made allowance in the comparative table drawn up, for a slight difference observed in their indications.

^{page 22 note *} I occasionally noticed that after adding the salts, the first deposition of moisture could not be noticed before the surface of the glass had imperceptibly become quite moist, and the temperature much below the true dew point; but this, of course, was easily corrected, by transferring the liquid to a dry vessel, and proceeding in the usual way.

^{page 22 note †} The manner recommended to me is to scrape off with a knife from a piece of good and light rotten-stone, some very fine powder, to place this on a piece of woollen cloth, such as the rind of broad cloth, to mix this with a little olive-oil, and rub the bottle with this mixture, then to rub it with a piece of cotton cloth, on which a little of the fine powdered rotten-stone has been laid, and to finish by rubbing with a piece of soft cloth, without either powder or oil, till a bright surface is obtained. A piece of chamois leather is also kept with which to clean it, when the paste is not used.

^{page 23 note *} As window sills are often inclined and uneven, one or two little wedges of wood may be employed to produce steadiness of attachment. Pieces of wood may be used to prevent fine tables from receiving injury, in attaching the clamp to them.

^{page 23 note †} Zehnterband, s. 135.