"We had kept company quite long enough with the old, now broken-up floe, so worked ourselves a little way astern after dinner, as the ice was beginning to draw together. Towards evening the pressure began again in earnest, and was especially bad round the remains of our old floe, so that I believe we may congratulate ourselves on having left it. It is evident that the pressure here stands in connection with, is perhaps caused by, the tidal wave. It occurs with the greatest regularity. The ice slackens twice and packs twice in 24 hours. The pressure has happened about 4, 5, and 6 o'clock in the morning, and almost at exactly the same hour in the afternoon, and in between we have always lain for some part of the time in open water. The very great pressure just now is probably due to the spring-tide; we had new moon on the 9th, which was the first day of the pressure. Then it was just after mid-day when we noticed it, but it has been later every day, and now it is at 8 P.M." The theory of the ice-pressure being caused to a considerable extent by the tidal wave has been advanced repeatedly by Arctic explorers. During the Fram's drifting we had better opportunity than most of them to study this phenomenon, and our experience seems to leave no doubt that over a wide region the tide produces movement and pressure of the ice. It occurs especially at the time of the spring-tides, and more at new moon than at full moon. During the intervening periods there was, as a rule, little or no trace of pressure. But these tidal pressures did not occur during the whole time of our drifting. We noticed them especially the first autumn, while we were in the neighborhood of the open sea north of Siberia, and the last year, when the Fram was drawing near the open Atlantic Ocean; they were less noticeable while we were in the polar basin. Pressure occurs here more irregularly, and is mainly caused by the wind driving the ice. When one pictures to one's self these enormous ice-masses, drifting in a certain direction, suddenly meeting hinderances--for example, ice-masses drifting from the opposite direction, owing to a change of wind in some more or less distant quarter--it is easy to understand the tremendous pressure that must result.