when the ship is descending without power at the rate of 250 ft. per minute. This pressure, while inadequate for normal flight, is sufficient to permit satisfactory hand› ling of the ship during landing operations. 

Instructions for starting the blower for airships K-3 thru K-98 are given on p~ _ ge 44. 

## (j) Shifting Air 

During flight, it may bec.ome necessary to adjust the relative inflation of the two ballonets •in order to change the trim of the ship. This is done by operating the air valves and dampers manually. 

In trimming the ship in this manner, it may be well to consider air as ordinary ballast, the effect of transferring air being the same as that of transferring any ballast. 

## (k) Blowing Air Into The Gas 

In emergency cases where a large amount of gas has been lost, such as when the ship is descending after having over› shot its pressure height, and the ballonets, even when fully inflated, cannot keep up the. pressure of the envelope, it may become necessary to blow air into the gas. 

This may be done by untying the sleeve connecting the air chamber to the envelope. This sleeve is located above 

