One would think that the civilized world had had lessons enough, ever since that seventh century burning of the Alexandrian library by the Caliph Omar, with that famous but apocryphal rhetorical dilemma, put in his mouth perhaps by some nimble-witted reporter:--"If these books agree with the Koran, they are useless, and should be burned: if not, they are pernicious, and must not be spared." But the heedless world goes carelessly on, deaf to the voice of reason, and the lessons of history, amid the holocausts of literature and the wreck of blazing libraries, uttering loud newspaper wails at each new instance of destruction, forgotten in a week, then cheerfully renewing the business of building libraries that invite the flames. Nothing here said should be interpreted as advice not to insure any library, in all cases where it is not provided with iron cases for the books, or a fire-proof building. On the contrary, the menaced destruction of books or manuscripts that cannot be replaced should lead to securing means in advance for replacing all the rest in case of loss by fire. And the experience of the past points the wisdom of locating every library in an isolated building, where risks of fire from other buildings are reduced to a minimum, instead of in a block whose buildings (as in most commercial structures) are lined with wood. You will perhaps attach but small importance at first thought, to the next insidious foe to library books that I shall name--that is, wetting by rain. Yet most buildings leak at the roof, sometime, and some old buildings are subject to leaks all the time. Even under the roof of the Capitol at Washington, at every melting of a heavy snow-fall, and on occasion of violent and protracted rains, there have been leaks pouring down water into the libraries located in the old part of the building. Each of these saturated and injured its quota of books, some of which could only be restored to available use by re-binding, and even then the leaves were left water-stained in part. See to it that your library roof is water-tight, or the contents of your library will be constantly exposed to damage against which there is no insurance.