The materials extant comprise occasional travellers’ notes, fairly numerous newspaper items, and quite voluminous manuscript collections of appraisals and bills of sale, all of which require cautious discrimination in their analysis.[20] The appraisals fall mainly into two groups:  the valuation of estates in probate, and those for the purpose of public compensation to the owners of slaves legally condemned for capital crimes.  The former were oftentimes purely perfunctory, and they are generally serviceable only as aids in ascertaining the ratios of value between slaves of the diverse ages and sexes.  The appraisals of criminals, however, since they prescribed actual payments on the basis of the market value each slave would have had if his crime had not been committed, may be assumed under such laws as Virginia maintained in the premises to be fairly accurate.  A file of more than a thousand such appraisals, with vouchers of payment attached, which is preserved among the Virginia archives in the State Library at Richmond, is particularly copious in regard to prices as well as in regard to crimes and punishments.

[Footnote 20:  The difficulties to be encountered in ascertaining the values at any time and place are exemplified in the documents pertaining to slave prices in the various states in the year 1815, printed in the American Historical Review, XIX, 813-838.  In the gleaning of slave prices I have been actively assisted by Professor R.P.  Brooks of the University of Georgia and Miss Lillie Richardson of New Orleans.]

The bills of sale recording actual market transactions remain as the chief and central source of information upon prices.  Some thousands of these, originating in the city of Charleston, are preserved in a single file among the state archives of South Carolina at Columbia; other thousands are scattered through the myriad miscellaneous notarial records in the court house at New Orleans; many smaller accumulations are to be found in county court houses far and wide, particularly in the cotton belt; and considerable numbers are in private possession, along with plantation journals and letters which sometimes contain similar data.

Now these documents more often than otherwise record the sale of slaves in groups.  One of the considerations involved was that a gang already organized would save its purchaser time and trouble in establishing a new plantation as a going concern, and therefore would probably bring a higher gross price than if its members were sold singly.  Another motive was that of keeping slave families together, which served doubly in comporting with scruples of conscience and inducing to the greater contentment of slaves in their new employ.  The documents of the time demonstrate repeatedly the appreciation of equanimity as affecting value.  But group sales give slight information upon individual prices; and even the bills of individual sale yield much less than a statistician could wish.