In the construction of the Tables of Policy Values for the Messenger Prize Essay (1868), the operations were considerably facilitated by the use of different modes of working applicable to the different data at hand; an explanation of which forms the subject of the present paper.

In the formation of Tables the great objects to be attained are accuracy and facility of working. These may be acquired in a high degree if it be possible by means of a simple operation to deduce each value in succession from the one which immediately precedes it, in which case the chances of error are reduced to a minimum, and the construction facilitated by the work not requiring to be checked except at distant intervals.