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274 G P G tifie men of his own country, and he managed, either through original contributions or by translations of memoirs of approved value already printed, to secure for many years an adequate representation of the scientific work of other lands. So true is this that, for years after the beginning of Poggeudorff s editorship, the tables of con tents of his annual volumes read like an index of the history of physical science. In the course of his fifty-two years editorship of the Anna! tit Poggendortf could not fail to acquire an unusual acquaintance with the labours of modern men of science. This knowledge, joined to what he had gathered by historical reading of equally unusual extent, he carefully digested and gave to the world in his Biographisch- Uterarisches Handbuch zur Geschichte der Exacten Wissen- schaften, containing notices of the lives and labours of mathematicians, astronomers, physicists, chemists, minera logists, geologists, iSrc., of all peoples and all ages. The two volumes of this work contain an astounding collection of facts invaluable to the scientific biographer and his torian ; they form in fact the basis of the yet unwritten history of physical science. We possess a small fragment of such a history in the form of lectures delivered by Poggendorff himself at Berlin ; and probably he had con templated at one time writing a continuous narrative ; but even his long life was too short for the double task of collecting and using the material. Poggendorff was a physicist of high although not of the very highest rank. He was wanting in mathematical ability, and never displayed in any remarkable degree the still more important power of scientific generalization, which, whether accompanied by mathematical skill or not, never fails to mark the highest genius in physical science. He was, however, an able and conscientious experimenter. He was very fertile and ingenious in devising physical apparatus, and contributed greatly in the earlier part of his life to enrich the resources of experimental science. Contemporaneously with SchAveigger, he succeeded in greatly increasing the sensitiveness of the galvanometer by introducing the multiplying coil, and he made important improvements on that particular type of this instru ment which is usually called the sine galvanometer. To him (according to Wiedemann) we owe the use of binding screws in most of their various forms. He invented the " Inversor " for rapidly alternating the direction of a voltaic current, and the " Wippe " for throwing a number of voltaic or electrolytic cells suddenly into " series " or into " multiple arc " ; and to him is due the suggestion of the telescope and mirror method for reading galvanometers and other physical instruments, a device which has proved rery valuable in all branches of physical science. Poggendorff s contributions to physics were published for the most part in his own journal. They form an important part of the scientific work of the 19th century ; but it would be difficult in a few words to characterize them inasmuch as they do not constitute a single coherent group or even a few coherent groups of connected researches. By far the greater and more important part of his work related to electricity and magnetism. As specimens we may mention his investigations into the working of Holtz s machines, and his variations on their construction ; his researches on the resistance and electro motive force of electrolytic cells, along with which ought to be noticed his admirable method of comparing electro motive forces by "compensation "; and finally his researches on magnetism and diamagnetism. Poggendorff s literary and scientific reputation speedily brought him honourable recognition. In 1830 he was made royal professor and in 1834 Hon. Ph.D. and extra ordinary professor in the university of Berlin, and in 1839 member of the Berlin Academy of Sciences. He ultimately became a member of many foreign societies, and received more than the usual share of the orders bestowed by Continental nations for scientific merit. Dur ing his lifetime many offers of ordinary professorships were made to him, but he declined them all, devoting himself to his duties as editor of the Anmilen, and to the pursuit of his scientific researches. He died at Berlin on January 24, 1877. POGGIO (1380-1459). Gian Francesco Poggio Brac- ciolini, eminent in the annals of the revival of learning, was born in 1380 at Terranova, a village in the territory of Florence. He studied Latin under John of Ravenna, and Greek under Manuel Chrysoloras. His distinguished abilities and his dexterity as a copyist of MSS. brought him into early notice with the chief scholars of Florence. Coluccio Salutati and Niccolo de Niccoli befriended him, and in the year 1402 or 1403 he was received into the service of the Roman curia. His functions were those of a secretary ; and, though he profited by benefices conferred on him in lieu of salary, he remained a layman to the end of his life. It is noticeable that, while he held his office in the curia through that momentous period of fifty years which witnessed the councils of Constance and of Basel, and the final restoration of the papacy under Nicholas V., his sympathies were never attracted to ecclesiastical affairs. Nothing marks the secular attitude of the Italians at an epoch which decided the future course of both Renaissance and Reformation more strongly than the mundane pro clivities of this apostolic secretary, heart and soul devoted to the resuscitation of classical studies amid conflicts of popes and antipopes, cardinals and councils, in all of which he bore an official part. Thus, when his duties called him to Constance in 1414, he employed his leisure in exploring the libraries of Swiss and Swabian convents. The treasures he brought to light at Reichenau, Wein- garten, and above all at St Gall, restored many lost master pieces of Latin literature, and supplied students with the texts of authors whose works had hitherto been accessible only in mutilated copies. In one of his epistles he describes how he recovered Quintilian, part of Valerius Flaccus, and the commentaries of Asconius Pedianus at St Gall. MSS. of Lucretius, Columella, Silius Italicus, Manilius, and Vitruvius were unearthed, copied by his hand, and communicated to the learned. Wherever Poggio went he carried on the same industry of research. At Langres he discovered Cicero s Oration for Cxcina, at Monte Cassino a MS. of Frontinus. He also could boast of having recovered Ammianus Marcellinus, Nonius Mar- cellus, Probus, Flavius Caper, and Eutyches. If a codex could not be obtained by fair means, he was ready to use fraud, as when he bribed a monk to abstract a Livy and an Ammianus from the convent library of Hersfeld. Resolute in recognizing erudition as the chief concern of man, he sighed over the folly of popes and princes, who spent their time in wars and ecclesiastical disputes when they might have been more profitably employed in reviving the lost learning of antiquity. This point of view is eminently characteristic of the earlier Italian Renaissance. The men of that nation and of that epoch were bent on creating a new intellectual atmosphere for Europe by | means of vital contact with antiquity. Poggio, like a still more eminent humanist of his age, TEneas Sylvius Piccolomini, was a great traveller, and wherever he went he brought, like vEneas Sylvius, enlightened powers of observation trained in liberal studies to bear upon the manners of the countries he visited. We owe to his pen curious remarks on English and Swiss customs, valuable notes on the remains of antique art in Rome, and a

singularly striking portrait of Jerome of Prague as he