said ship may be one foot and a half thick, that is made with cross beams within and without, with planks in contrary directions. And this ship must have attached to it, a foot below the water, an iron-shod spike of about the weight and size of an anvil; and this, by force of oars may, after it has given the first blow, be drawn back, and driven forward again with fury give a second blow, and then a third, and so many as to destroy the other ship.
The use of swimming belts.
1117.
A METHOD OF ESCAPING IN A TEMPEST AND SHIPWRECK AT SEA.
Have a coat made of leather, which must be double across the breast, that is having a hem on each side of about a finger breadth. Thus it will be double from the waist to the knee; and the leather must be quite air-tight. When you want to leap into the sea, blow out the skirt of your coat through the double hems of the breast; and jump into the sea, and allow yourself to be carried by the waves; when you see no shore near, give your attention to the sea you are in, and always keep in your mouth the air-tube which leads down into the coat; and if now and again you require to take a breath of fresh air, and the foam prevents you, you may draw a breath of the air within the coat.
[Footnote: AMORETTI, Memorie Storiche, Tav. II. B. Fig. 5, gives the same figure, somewhat altered. 6. La canna dell' aria. Compare Vol. I. No. I. Note]
On the gravity of water.
1118.
If the weight of the sea bears on its bottom,