on board the ship in which his machine was to be tried, Sir Jacob did not appear, but hearing that the company were pleased afterwards told Dr. Desaguliers that at the next experiment he (the Doctor) need not attend, as the carpenter could manage the ventilation.

When the second trial came off, Sir Jacob had scuttle holes cut at each end of the ship and then hoisted enormous windsails, and when, as might naturally be expected, he found that more air came through his windsails, which were about 2'.6" diameter than through the Doctor's tubes, which were 5"X3'; he said he could not stay longer, and that he was sorry the machine had answered no better. Sir Jacob, however, sent his "humble duty" to Dr. Desaguliers, and thought his invention might be a very pretty thing in a house.

The Lords of the Admiralty never came near nor gave themselves any trouble about it, and so the Doctor found his invention would not be used in the Navy.

The next person who came forward in the cause of ventilation for the Navy, was

Mr. Sutton, a brewer by trade. He made use of the fire which cooked the provisions of the ship's company as the motive power, laying pipes from all parts of the ship to the ashpit under the grate. When the ashpit-door was closed no air could get to the fire except throught the pipes.

The result was considered satisfactory, and the apparatus was ordered to be fitted up on board the Norwich man-of-war.

Mr. Sutton had also to contend with Sir Jacob Ackworth, but he had found powerful friends in Dr. Mead, the King's Physician, and Sir Charles Wager, so that the old knight's opposition was rather passive than

active.

This, I believe, is one of the first, if not the first, instance of the scientific use of the common fire as the power for ventilating any structure. This method has been called thermo-ventilation by Mr. Bernan, to whose work, as well as to those of the inventors whose names I have mentioned, I am indebted for many of the particulars given above.

However successful Mr. Sutton may have

been in getting his apparatus fixed, he failed when he applied to the Admiralty for some reward for his sevices; they simply took no notice of him or his petition, although the Norwich had returned to England from the Guinea Coast, with the loss of only two men, and the Captain reported her singularly healthy.

Meanwhille, a certain Dr. Hales had been pressing an invention of his own upon the notice of my Lords. This he called a ship's lungs. The machine was, in fact, a magnified bellows, differing somewhat in construction from common bellows certainly, but the same as far as action was concerned. It consisted of a large square case with valves, enclosing a hinged midriff, which rose and fell by the action of a long handle or lever, worked by some of the ship's company. The whole machine was cumbersome, requiring about four men per hour to work it, and could not, certainly, compare with the blowing-wheel of Dr. Desaguliers. It soon fell into disuse, and became a thing of the past.

Mr. Sutton, who had at last got £100

from the Admiralty, exulted over the failure of the ship lungs, but his triumph was short-lived, for, in the course of a few years, he found that he was left out in the cold also, and the old wind-sails were again on duty.

The illustrious names of Count Rumford and Sir H. Davy, as well as those of a host of other persons less celebrated, which figure in the annals of ventilation, attest the importance of the question. It is time, however, for me to take leave of this portion of my subject, on which volumes. might be written, and to consider the causes which make ventilation a necessity.

These may be classed under different heads, viz.: 1st, In private houses. The necessity for ventilation will arise from commonly (A) the presence of fires; (B) artificial light; (C) the presence of persons living in the house, that is from the air required by them, as well as the exhalations from their bodies, and (D) from badly constructed water-closets, cesspools and drains. 2d. In factories there will be, in addition to the above causes, the presence in the air

of a vast quantity of minutely-divided fibre and dust, which is highly prejudicial to the health of the workers, and also the fumes from chemicals, etc., where the manufacture of such is carried on. 3d. In sewers. The necessity of sufficient ventilation will almost entirely arise from the generation of poisonous gases by the putrid filth carried down. 4th. And in underground railways, the fires of the engines, and the saturation of air by the waste steam, will render ventilation, in certain cases, necessary.

Considering these cases in the above order, we have 1st, in dwelling houses (A), the presence of fires.

At first sight it would seem an error to include this under the head of causes which make ventilation necessary. As fires are often, indeed mostly, the only means of ventilation in private houses. But under the term I include not only the removal of foul air, but the supply of fresh, and from this point of view it will be seen that the common fire is a very great consumer of fresh air, and requires a supply of that