In conclusion, a word of thanks is due to Captain Brooke-Smith and Commander Hennessey of the Meteorological Section of the Air Ministry, for much valuable advice and assistance, both before we sailed and after our return home. APPENDIX IV HYDROGRAPHIC WORK _The following is a brief account of the hydrographic work carried out by_ COMMANDER WORSLEY, R.N.R., _assisted by_ LIEUT-COMMANDER JEFFERY, R.N.R., J. DELL, P.O., R.N., _and_ CAPTAIN G. V. DOUGLAS. The hydrographic equipment consisted, besides sextants, theodolites, chronometers and compasses, of three sounding machines—a Kelvin and two Lucas machines—a gyroscope compass, two rangefinders, and a wireless set. The Kelvin sounding machine has a 7-stranded steel wire ·35 of an inch in circumference and 300 fathoms long. It is intended for soundings to a depth of 100 fathoms, for which purpose thin glass tubes of chemicals are provided which record the pressure to that depth, but we frequently took soundings to 280 fathoms by stopping the ship and getting a perpendicular cast. The Lucas machine, which, in addition to having been lent to Sir Ernest Shackleton on his different expeditions and supplied to the French, German and Australian Antarctic Expeditions of 1908-10 and 1911 and also the Canadian Arctic Expedition of 1913, has done the major part of the work of exploring the profound depths of the world’s oceans, and is, I believe, easily the best machine to-day for the work. Ours had 6,000 fathoms Brunton wire, having a diameter of ·028 inches and weighing 12·3 lbs. per 1,000 fathoms, with a breaking strain of 200 lbs. We also had a 500-fathom Lucas, suitable for boat work, and with which I have always hoped at some time to sound, through a crevasse, for the thickness of the Great Antarctic ice sheet. The 6,000-fathom machine could also be used for kites, small balloons and other aerial work. The Sperry gyroscope compass worked well as far South as we went—69° 18´—but the liveliness of the vessel made the initial adjustments difficult, and the constant ramming and blows from the ice threw it out again. The new type of mercury ballistic with which it was fitted minimized much of the bad effects of the bumping. Add to this the small size of the vessel not enabling us to carry more fuel for the actuating dynamo, and the lateness of the season prevented us stopping often for the necessary time to steady it up. We can, however, say from our experience of it that in a slightly steadier vessel, with more time and dynamo fuel, that even in latitudes beyond 70° it would be most useful for quickly ascertaining the variation of the magnetic needles and, in conjunction with the rangefinder, for quickly making a chart of a coast or islands which the vessel might be passing. Much of our survey of Gough Island was so made. Our average time taken to get the gyro running correctly from the start was about six hours.