The climbers carried "Magnapole" compasses with luminous points, and sometimes a Mark VIII prismatic; these all worked well. The simpler compass is the more convenient for use on snow when goggles must be worn. A luminous liquid compass (Short & Mason) was found very useful on long reconnaissance rides. For the record of temperatures in camps Messrs. Negretti & Zambra had made three small pairs of maximum and minimum thermometers in leather travelling cases. These suffered some casualties, by theft, or being accidentally left out in the sun; and the pattern has been repeated for the second year's work. The heavier photographic equipment included an old and well-seasoned 71/2 x 5 Hare Camera, lent to the Expedition, but newly fitted by Messrs. Dallmeyer with a Stigmatic lens of 9 inches focal length, a negative telephoto lens of 4 inches focal length giving enlargement up to 6 times, and a set of Wratten filters. With this camera Mr. Wollaston secured some of the finest pictures taken on the Expedition. There were also two quarter-plate cameras for glass plates: a Sinclair Una camera fitted by Messrs. Dallmeyer with a Stigmatic lens of 5.3 inches focal length, and Adon telephoto lens; and a second Sinclair camera lent by Captain Noel. One or the other of these two was used by Mr. Mallory at many of the high camps, and both the Hare 71/2 x 5 and the Sinclair quarter-plate went to the 22,500-foot camp at the Lhakpa La: doubtless the greatest height yet attained by so large a camera as the former. The principal difficulty with these cameras was unsteadiness in a heavy wind when the telephoto lens was in use: and the tripods have been strengthened and the lens supports stiffened before they go out again. The plates were of two kinds: Imperial Special Rapid and Fine Grain slow. The latter were generally preferred, and could hardly have been better. The Imperial Dry Plate Company, who generously made and presented these plates to the Expedition, deserve special thanks for their skill and for their generosity. The cameras which used films were a Panoram Kodak of 5 inches focal length, with films 12 x 4 inches; a No. 1 Autograph Kodak, and two Vest Pocket Kodaks, all three fitted with Cooke lenses by Messrs. Taylor, Taylor & Hobson. The Panoram Kodak was used very successfully by Colonel Howard-Bury, and the splendid series of panoramas is the most useful, if not quite the most beautiful, set of photographs brought home. The smaller cameras were used by the climbing party with many good results. Finally it must be said that a large part of the best photographs were taken by Colonel Howard-Bury with his own 7 x 5 Kodak, and the results very generously placed at the disposal of the Committee. All the instruments were examined and tested at the National Physical Laboratory, and the thanks of the Committee are due to the Director and his staff, who gave most valuable advice and assistance. APPENDIX V