In the publication of the four parts which complete the present volume of the Scientific Memoirs, 1 have ventuted to make the experiment how far I might be able to succeed in supplying an auxiliary which, as was stated in the Advertisement prefixt to the First Part, appeared to be much needed for the progress and advancement of science in this country.
My own conviction of the utility of such a work has been much strengthened since I have been engaged in it, both by the importance of the materials that present themselves, and by the expressed opinions of persons most competent to judge. How great indeed the disadvantage must be, under which those are placed who are engaged in any branch of scientific inquiry, from being uninformed as to what is doing, or has been done, by our active and laborious neighbours on the Continent, must be obvious to every one : and the cases are numerous to which the remark of Lenz, p. 312, speaking of Ohm's theory of the galvanic battery, will apply,—that, although given to the world several years ago, yet, "being only published in the German language, it is unknown both in France and in England."With regard to the execution of the work, I must submit it to the candid judgement of those who are aware of the difficulty of the task,—having availed myself of the valuable suggestions with which I have been favoured in the selection of memoirs, and of the best assistance within my reach for their translation. I shall be satisfied if what has been done should render the present volume useful to science, and if what there is still to do should induce the public to enable me to continue the work. Hitherto, as I can hardly yet boast of the sale of 250 copies, I am very far from having been repaid the cost of publication, to say nothing of the care and labour which have been required: nor could I be expected, having now finished a volume, which, from the nature of its materials, may be considered a complete work in itself, to proceed further unaided, until I have ascer-