lamina of lead, upon which it was believed that the mercury would fasten itself and might thus be drawn out.  Avicenna objected to this that the mercury was liable to speedily pass into the ear so deeply as to be beyond the reach of the lead.  Gilbert suggests as an improvement of the treatment that a thin lamina of gold be substituted for the lead, “because mercury thirsts after gold as animals do after water, as it is held in the books on alchemy” (in libris allzinimicis).  This fact, too, he tells us can be easily demonstrated externally by placing upon a plate a portion of gold, and near, but not in contact with it, a little quicksilver, when the silver, he says, will at once “leap” upon the gold.  Avicenna suggests that the patient stand upon the foot of the side affected, lean his head over to the same side, steady it in that position with the hands, and then leap suddenly over upon the other foot—­demonstrating thereby his knowledge of both gravity and inertia.  Manifestly our “laboratory physicians” of the present day can assume no airs of priority!

The Compendium closes with two very sensible chapters on the hygiene of travel, entitled “De regimine iter agentium” and “De regimine transfretantium.”

In the hygiene of travel by land Gilbert commends a preliminary catharsis, frequent bathing, the avoidance of repletion of all kinds, an abundance of sleep and careful protection from the extremes of both heat and cold.  The strange waters may be corrected by a dash of vinegar.  Some travelers, he tells us, carry with them a package of their native soil, a few grains of which are added to the foreign waters, as a matter of precaution, before drinking.  The breakfast of the traveler should be light, and a short period of rest after a day’s travel should precede the hearty evening meal.  Leavened bread two or three days old should be preferred.  Of meats, the flesh of goats or swine, particularly the feet and neighboring parts, which, Gilbert tells us, the French call gambones, the flesh of domestic fowls and of the game fowls whose habitat is in dry places, is to be preferred to that of ducks and geese.  Of fish, only those provided with scales should be eaten, and all forms of milk should be avoided, except whey, “which purifies the body of superfluities.”  Fruits are to be eschewed, except acid pomegranates, whose juice cools the stomach and relieves thirst.  Boiled meats, seasoned with herbs like sage, parsley, mint, saffron, etc., are better than roasted meats, and onion and garlic are to be avoided.

The primitive conditions of land travel in the days of Gilbert are emphasized by his minute directions for the care of the feet, which he directs to be rubbed briskly with salt and vinegar and then anointed with an ointment of nettle-juice (urtica) and mutton-fat, or with a mixture of garlic, soap and oil.  If badly swollen, they should be bathed, before inunction, with a decoction of elder-bark and other emollients.