FIG. 4.—PERPETUAL MOTION WHEEL
In order that the wheel may do its work more speedily, place within the box a small rounded weight made of brass or silver of such a size that it may be caught between each pair of teeth; consequently as the movement of the wheel is continuous in one direction, so the fall of the weight will be continuous in the other. Being caught between the teeth of a wheel which is continuously revolving, it seeks the centre of the earth in virtue of its own weight, thereby aiding the motion of the teeth and preventing them from coming to rest in a direct line with the lodestone. Let the places between the teeth be suitably hollowed out so that they may easily catch the body in its fall, as shown in the diagram above. ([Fig. 4].)
Farewell: finished in camp at the siege of Lucera on the eighth day of August, Anno Domini MCCLXIX.
NOTES
EARLY REFERENCES TO THE MARINER’S COMPASS
The following are the passages referred to in the introductory notice:
Abbot Neckam (1157-1217), in his De Naturis Rerum, writes:
“The sailors, moreover, as they sail over the sea, when in cloudy weather they can no longer profit by the light of the sun, or when the world is wrapped up in the darkness of the shades of night and they are ignorant to what point their ship’s course is directed, these mariners touch the lodestone with a needle, which (the needle) is whirled round in a circle until when its motion ceases, its point looks direct to the north. (Cuspis ipsius septentrionalem plagam respiciat.)”
In his De Utensilibus, we read: