The rotation of the dome is again begun and the indicator is made to travel away from the zero, until at the end of about five minutes, it reaches “full.” After the first few minutes, it will be necessary to give an occasional breath of fresh air, otherwise an undesirable degree of cyanosis will result, but it must be done with great discretion, or struggling will ensue. At the end of about five minutes, anæsthesia should be fully established. A little extra ether is then poured into the chamber, the indicator pushed back to about “two” and the administration continued. One breath of fresh air is given in every three or four. Spells may be given with the bag off altogether, but during such periods the indicator will require to be advanced a little, and refills of ether provided more frequently than would be necessary if the bag were on. Hewitt’s-wide-bore. The principle of this is identical with that of the Clover, but the channels being wider, there is less mechanical interference with the ingress and egress of air. The actual construction differs also, in that to turn on the ether, instead of rotating the dome, one moves the indicator (_see_ Fig. 25). The instrument certainly gives results a little better than those obtainable by the Clover, but it is heavier, and rather more bulky. Ormsby’s Inhaler (_See_ Fig. 26). This consists of a facepiece, a cage made of wire or thin steel slips and containing a sponge; and lastly, a one gallon bag which fits over the cage. In the face-piece is an air vent, which can be either entirely closed, partially or entirely opened. [Illustration: FIG. 26.--Ormsby’s Inhaler. The cage for the sponge does not show in the figure, it projects upwards from the bag-mount, and is therefore enclosed in the bag.] To use the instrument, take out the sponge and warm it either by wringing it out of hot water, or better by leaving it a few minutes on the top of a hot steriliser. Push it back into the cage, open the air vent fully, and holding the inhaler upside down, pour on to the sponge a measure full (about half an ounce) of ether. Tell the patient to inhale deeply, and then catch the resulting expiration in the bag by quickly adapting the facepiece to the face at the appropriate second. After a few seconds, begin to close the air vent, when it will be found that the bag begins to wax and wane with each expiration and inspiration respectively. After the first three minutes, the inhaler must be removed, more ether poured in, the air vent opened again partially, and the inhaler again applied to the face. After full anæsthesia is induced, the air vent may constantly be left partially open. _N.B._--It must be observed that the air vent is not valved: it is merely an opening through which part of the respired air may pass in and out without going near the ether sponge.