tcntion while a student at the university, and on that study he bestowed many
of his spare hours during his ministry. He has left behind him voluminous
manuscript specimens of his labours; but it will probably be now considered
better evidence of his early proficiency, that in 1720 he was chosen assistant to
Dr Gregory, then suffering under bad health. Wallace was, in 1733, appointed
one of the ministers of the Greyfriars' church in Edinburgh. The countenance
of the government, which he had previously obtained, he forfeited in 1736, by
refusing to read in his church the act for the more effectually bringing to justice
the murderers of Porteous, which the zealous rage of the ministry and the house
of peers had appointed to be read from the pulpit. He was in disfavour during
the brief reign of the Walpole ministry; but under their successors was intrusted
with the conduct of ecclesiastical affairs. The revolution in the ministry happened at a moment when Dr Wallace was enabled to do essential service to his
country, by furthering the project of the Ministers' Widows' Fund. The policy
of that undertaking was first hinted at by Mr Mathieson, a minister of the high
church of Edinburgh; Dr Wallace in procuring the sanction of the legislature,
and Dr Webster, by an active correspondence, and the acquisition of statistical
information, brought the plan to its practical bearing, by apportioning the rates,
&c., and afterwards zealously watched and nurtured the infant system. As the
share which Dr Wallace took in the promotion of this measure is not very well
known, it may be mentioned, that it appears from documents in the office of the
trustees of the Ministers' Widows' Fund, that he was moderator of the General
Assembly in 1743, which sanctioned the measure. In the ensuing November
lie was commissioned by the church, along with Mr George Wishart, minister of
the Tron church, to proceed to London, and watch the proceedings of the legislature regarding it. He there presented the scheme to the lord advocate, who
reduced it to the form of a Bill. The corrections of Messrs Wallace and Wishart appear on the scroll of the Bill.
In 1744, Dr Wallace was appointed one of the royal chaplains for Scotland. He had read to the Philosophical Society of Edinburgh, of which he was an original member and active promoter, a "Dissertation on the numbers of Mankind in ancient and modern times," which he revised and published in 1752. In this work he was the first to apply to purposes of investigation one of those truisms which, however plain, are never stated until some active mind employs them as foundations for more intricate deductions, that the number of human beings permanently existing in any portion of the earth must be in the ratio of the quantity of food supplied to them. The explanation of this truth by Dr Wallace has been acknowledged by Malthus, and the work in which it was discussed has acquired deserved fame for the mass of curious statistical information with which the author's learning furnished it; but in the great theory which he laboured to establish, the author is generally allowed to have failed. He maintained, as a sort of corollary to the truth above mentioned, that where the greatest attention is paid to agriculture, the greatest number of human beings will be fed, and that the ancients having paid greater attention to that art than the moderns, the world of antiquity must have been more populous than that of modern days. Were all food consumed where it is produced, the proposition would be true, but in a world of traffickers, a sort of reverse of the proposition may be said to hold good, viz., that in the period where the smallest proportion of the human beings on the surface of the earth is employed in agriculture, the world will be most populous, because for every human being that exists, a quantity of food sufficient to live upon must be procured; for procuring this food the easiest method will always be preferred, and therefore when the proportion of persons engaged in agriculture is the smaller, we are to presume, not
