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Rh logical computations shown to be necessary for the complete solution of the problem.

The remainder of the treatise is an exhaustive account of the methods of scientific investigation. What is most remarkable in this portion of the work is the combination of extensive and accurate knowledge of facts with perfect command of the most general principles. As a writer on scientific method, Prof. Jevons is fairly entitled to the credit of being a peer of predecessors so eminent as Herschel, Whewell, and Mill. He has given the fullest and best exposition of the methods actually employed by the greatest scientific workers, and has collected from all quarters a mass of most richly varied illustration.

The concluding book of the treatise is a brief but pregnant essay on the results and limits of scientific method. The outcome of the author's careful analysis of induction, the essentially probable character of what are called natural laws, is applied as a corrective to the rash scientific generalizations indulged in by many writers, and to the equally rash deductions from them. At the present time his. weighty remarks on the supposed contradiction between natural law and divine providence in any form are peculiarly deserving of attention.

Prof. Jevons published a volume, in 1875, entitled "Money, and the Mechanism of Exchange," forming part of "The International Scientific Series." It contains a lucid and admirably-written exposition of the nature and functions of money, the principles of circulation, the various forms of credit documents, and the elaborate mechanism (banks, check, and clearing systems) by which money exchanges are facilitated. Careful and complete historical notices are also given with regard to the various metallic currencies, modes of coinage, and regulations of issue, while technical matters, such as the qualities requisite for good metallic currency, the loss of weight in coins by usage, and the cost of keeping up the currency, receive due attention. His last publication was the little compendium of logic called "The Logic Primer," intended to give general readers some idea of this science.

In 1868 Prof. Jevons was appointed an Examiner in Political Economy in London University. In 1870 he was President of the Economic Section (Section E) of the British Association at its Liverpool meeting. In 1872 he was elected a Fellow of the Royal Society. In 1874 and 1875 he was an Examiner for the Moral Sciences Tripos at Cambridge. In the year 1876 the Senatus Academicus of Edinburgh University conferred upon him the honorary degree of LL. D.; and in the same year he was appointed Examiner in Logic and Moral Philosophy in London University. In March, 1876, Prof. Jevons announced his resignation of his professorship at Owens College; and in October, 1876, he entered upon the duties of the distinguished position to which he had been chosen, and which he now occupies, as Professor of Political Economy in University College, London.