ten o’clock
In order to fix the angle obtained , he fastened with thorns the two pieces of wood on a third placed transversely , so that their separation should be properly maintained . That done , there was only the angle to calculate by bringing back the observation to the level of the sea , taking into consideration the depression of the horizon , which would necessitate measuring the height of the cliff . The value of this angle would give the height of Alpha , and consequently that of the pole above the horizon , that is to say , the latitude of the island , since the latitude of a point of the globe is always equal to the height of the pole above the horizon of this point . The calculations were left for the next day , and at ten o'clock every one was sleeping soundly . The next day , the 16th of April , and Easter Sunday , the settlers issued from the Chimneys at daybreak , and proceeded to wash their linen . The engineer intended to manufacture soap as soon as he could procure the necessary materials -- soda or potash , fat or oil . The important question of renewing their wardrobe would be treated of in the proper time and place .