3. The season of the year for sledging must depend on the climate of particular Arctic localities, and the capacity of the men to endure low temperatures during the night-camping, and driving snow during the march. It is advisable, when more than one year is to be spent in the ice, to begin the more extended sledge-journeys in the first year, because the capacities of Europeans to endure cold rather decrease than increase. Sir John Ross, for example, says that his people at the beginning of a third winter were incapable of bearing hardships, especially those of travelling on the ice. The best season for sledging must always be that time of the year when snow-storms are infrequent, for even a healthy and seasoned party will more easily confront a very low temperature than driving snow-storms. As a rule, these conditions are found most perfectly in autumn; and I do not understand the objection which Hayes makes to this season as being the most damp; whereas as a matter of fact it is the least so. Autumn journeys are preferable to those in spring, both with respect to climate and the state of the road; only they must be commenced early, on account of the rapidly decreasing length of the days.[27] The darkness of winter puts an end to all sledging, and the excessive cold of spring renders it difficult. Summer makes it impossible by breaking up the land-ice, or impedes it by transforming the snow into thaw-water and sludge. Next to autumn, therefore, the latter part of March, all April, and a part of May, are most adapted for this purpose. It must at the same time be remarked, that Captain Lyon (1822) and Dr. Kane regarded March as peculiarly dangerous on account of the prevalence of storms. 4. Next to the season, the state of the snow road, depending on the hardening action of wind and cold, has to be considered. The cold should not vary more than from -2° to -24° F., because greater frost transforms the smooth evaporating surface of snow into a rough plain, bestrewed with sharp pointed crystals, so that the sledge instead of gliding along encounters the friction, as if of a sandstone surface, and stops at the least obstacle. Snow of an ivory-like smoothness rarely occurs; on the contrary, we find the snow in deep layers as fine as powder, into which we sink knee-deep, or among barriers of hummocks, miles in extent, which impose enormous détours in the transport of the baggage. During the journey from 2° to 13° below zero F. constitutes the pleasantest temperature, and even the nights, under this condition, are passed without inconvenience by a party inured to exposure. Snow-storms, however, in their mildest form—snow-drifting—are, at this moderate temperature, distressing and dangerous. In fact, among all the contingencies which may occur during a Polar expedition, there is no severer test of enduring perseverance than dragging a sledge in the face of drifting snow at a temperature from 13° to 35° below zero F.