Volumes of transactions and proceedings of learned societies usually have a market value, which fluctuates much less than is usually the case. These being supplied to members only, and rarely published for purposes of sale, may be said to be both privately printed and limited in issue at the same time. As a rule they increase proportionately in value as the series becomes more complete, and a point once reached, they generally maintain it. Hence works of this character are safe investments--perhaps the safest of any. The result of every investigation into the causes which regulate the value of books has shown conclusively that no publication is of great worth merely _because_ it is scarce. The scarcity is a secondary and not a primary cause. Highly appreciated English publications of the sixteenth and two following centuries may be counted by thousands; but the number of inferior treatises, which have long ago sunk into eternal oblivion, which never were of any value, and never will be, are as the sand on the sea-shore. However scarce and valuable a book may be, it must be remembered that the element of perfection has yet to be taken into account. It does not by any means follow that, because a copy of one of Shakespeare's 4tos is worth L300, another copy of the same 4to edition will be of equal value. It may be worth more or less, and here it is that the critical eye of the _connoisseur_ and dealer tells. Defects, such as a tear in the cover or any of the leaves, stains, worm-holes, and the like, detract from the value; if these are entirely absent, the value may, on the contrary, be raised above the average. The fact of a rare book being "uncut," and in the original sound binding, clean, and free from blemishes, considerably add to its value.