292 APPENDIX. 



was well covered with canvas, and formed another condenser. Two 

 illuminators were taken out abreast the foremast, one on each side, and 

 casks inverted, with a pad of oakum, to prevent the access of air. Under 

 these fittings we derived deck condensers to the amount of 4200 cubic 

 feet. But to prevent the ingress of cold air from without, the porch 

 was constructed by an aperture sufficient for one man, and guarded by 

 falling vertical screens. The first landing outside was on the deck level, 

 where the accommodation ladder led aft to the floe ; there a door with 

 weight and pulley kept all secure ; this passage, therefore, was rectan- 

 gular, and could not lead in any cold air, as it would escape under the 

 lower ladder, which was above the level of the upper side of the door.* 

 The difference resulting was very decided : comfort and dryness pre- 

 vailed between decks, and the quarter-deck enjoyed generally a still air 

 with a temperature twenty degrees higher. The Plate annexed will, 

 1 trust, sufficiently explain these fittings. 



The framework might very easily be fitted before leaving England, 

 and the short planks be stowed away on deck until required. Even 

 when complete the entire area exposed above the gunwhale of the 

 ' Assistance' was only thirty-nine yards, about equivalent to three feet 

 oft" the foot of the mainsail. When secured for winter, the tilt-housing 

 would be seven feet above this, fore and aft. 



D. 



Weight and Analysis of Cubes of Salt Water or Floe Ice. 



The cubes were taken by accurate gauges from large masses of ice, 

 lifted from the floe during the period at which it became permanently 

 solid for the season. They were taken from the upper, centre, and in- 

 ferior portions, so as to afford distinct evidence as to their power of 

 retaining water and of the amount due to evaporation after exposure. 



As the results of Table I. (p. 295) afford materials for the purposes of 

 any one inclined to investigate, I shall offer no observation at present, 

 but for the use of the general reader they have been reduced to the value 

 of a cubic inch ; and, although they were kept within our housing, on 

 a shelf on deck, it will be apparent, so far as they could be minutely 

 weighed, they appeared to gain and lose without satisfactory reason. 



Water from the same ice has been analysed by Dr. Thompson, M.D., 

 which is also given in the Tables following. 



* Fide dotted line Plate ^TX 



