Theatrum naturae et artis

(a) This is evident in glass, which transmits neither water nor denser air, yet remains open to solar rays: in coals, which have pores and tubes principally according to their length: in red coral, which begins to shed its redness into hot white wax both inside and out: in leather, which transmits water and mercury, etc.

(b) Magnetic effluvia act through glass, specular stone, brass, mercury, etc.

4.

Those effluvia can be hindered, and the pores of the body themselves variously obstructed.

Thus, magnetic effluvia can not only be hindered but also completely removed. Embalmings belong here, both natural, via amber etc., and various artificial ones, in embryos and others.

II. On Motion.

I.

Where the fundamental mechanical machines and their powers must be known to us: namely, the three types of levers (a), the wheel and axle (b), the various types of pulleys (c), the inclined plane (d), the wedge (e), the screw (f), and that new one which they call the bladder-machine (g).