researches difficult, and to give them the character of simple geological reconnaissances. In new countries, the first thing is to obtain a sketch approximating to the truth, and afterwards to proceed to detailed studies.

It was during this period, from 1842 to 1862, that the system of coloring geological maps underwent a complete change. Till then everything was done by hand, and seldom with care. Maps were colored rapidly, and tints varied not only from one copy to another, but also on the same map, some parts being a shade lighter or darker than others; besides, traces left by the brushes added to the imperfection of the work. Finally, the overlapping of one color on another at the limits of the different systems delineated on the map often took such alarming proportions that it was impossible to tell to what formation considerable belts of country were referred. It was only by the skill derived from practice that the defects of hand-coloring were much diminished. It may be said that the geological survey of the United Kingdom of Great Britain and Ireland attained the highest possibilities of the method by forming a special corps of colorists who did nothing else for years, and by being very strict in the acceptance of the colored sheets, every one that had an apparent defect being invariably rejected.

As early as 1841 attempts at colored printing had been tried by Major Le Blanc, chief of the office of topographical engineers at Paris. This was his method: He used a sheet of tin-foil similar to that employed in the manufacture of looking-glasses, on which he fixed a proof of the map or geological section which he wished to reproduce. They were then cut out simultaneously, which gave a tin pattern of the formation. Then the color was placed on it by means of brushes prepared for the "lucidonique" method of painting, and the maps were printed under a press. This method from the first secured promptness, exactness, and cheapness of coloring.

The first sheet colored by this system of "poncis découpés," with mechanical impressions, represents "Coupes géologiques et topographiques des environs de Paris," made for the use of the military engineers, in the location of the fortifications of Paris, created under Louis Philippe. Shortly afterward Messrs. Le Blanc and Raulin undertook to color by this system a geological map in one sheet, "grand aigle," which ap. peared in 1843 with the title "Carte géognostique du Plateau tertiaire Parisien," by Victor Raulin. Then Major Le Blanc undertook the im pression in colors of the "Carte géologique du globe terrestre," by Boué, in one sheet. It is dated Paris, 1845, and bears this note: "Sous les auspices et la direction de la Société géologique de France par les soins et procédés de M. Le Blanc, vice-secrétaire." The execution took longer than was expected, and the map was not given to the public until the spring of 1846. The results obtained were quite defective, both as to the character of the colors, and exactness in outline, several colors her failing to meet or overlapping each other. However, these first

attempts were quite encouraging; especially as the cost was much less than by the hand process.

In April, 1846, I offered to the Société géologique de France for publication in its memoirs, my work entitled "Recherches géologiques sur le Jura Salinois," with a geological map of the country round Salins, scale 1:80,000, taken from the "Carte dite d'État-Major." Having been accepted by the committee on publications, Major Le Blanc offered to try his process of mechanical coloring, his offer was accepted, and my geological map of the Jura Salinois was the first printed in color that appeared in the publications of the Société géologique de France. The execution occupied 1846 and 1847, and the memoir, with the map, appeared in January, 1848. It has the same defects as the map of Boué, only they are more prominent because of the large scale.

The multiplication of geological maps, and the difficulties of satisfactory and rapid coloration by hand, rendered the invention of improved methods more and more important. Dufrénoy and Élie de Beaumont, after the publication of their great geological map of France in six sheets, began the trial of lithographic coloring at the Royal press of Paris, on a map called: "Tableau d'assemblage des six feuilles de la carte géologique de France," in a single sheet, scale of 1:2,000,000. Previously this "Tableau d'assemblage," colored by hand, had been placed at the end of the first volume, 4to, of the "Explication de la carte géologique de France," 1841. The copies of this volume distributed from 1841 to 1853 all contain this map colored by hand. But after 1853, or at the beginning of 1854, there appeared at the end of the volume which still bears the date: "Paris, Imprimerie Royale, MDCCCXLI," the map of the "Tableau d'assemblage," with the inscription to the right at the bottom of the map; "Lithographie de l'Imprimerie Imperiale.” This chromolithographic map of the imperial press was a success; the colors are brilliant and uniform and do not overlap each other. All the copies of Volume I of the "Explication de la carte géologique de France,” of Dufrénoy and Elie de Beaumont, since distributed, have this chromolithographic map.

Before we leave the "Imprimerie Nationale de France" let us mention the beautiful geological maps that have been made there, and whose execution has nowhere been surpassed, not even in these last years of progress of chromolithography. First, the "Carte géologique de la Belgique et des contrées voisines" by André Dumont, one sheet, 1855, a real masterpiece of coloring, especially if we consider the numerous superpositions of simple colors, which determine the greater part of the forty-two different tints of the tabular view of the map. The "Carte géologique de l'Europe," also by André Dumont, in four sheets, 1855-1857, is another fine example of coloring, far superior to the one made at the same time at Edinburgh by Keith Johnston for Sir Roderick Murchison's and Nicol's "Geological Map of Europe" in four sheets, 1856. Finally, the maps of the Etat-Major, scale of 1 : 80,000, used by the service of the

"Carte géologique détaillée de la France" have been colored by chromolithography since 1877, instead of coloring by hand employed up to that time.

Many improvements have been added to the first methods employed in 1854. The most important consists "in placing on metal by putting in relief the sheets of a map, and in operating the impression in colors under the typographical presses." From the Imperial press, chromolithography soon extended to private industry. In Paris, Messrs. Lemercier & Cie. printed chromolithographically, in May, 1855, the "Carte géologique des États-Unis et des Provinces anglaises de l'Amérique du Nord," by Jules Marcou, and in August the "Carte géologique du Canada," by W. E. Logan.

In Germany analogous attempts, by means of lithographical impressions in oil colors were made at the same time. In 1842 two chromolithographic geological maps appeared, namely: "Carte géognostique du Taurus et de ses environs," in folio, by M. J. Russegger, published at Stuttgart; and the geological wall map of Germany by Woelter, published at Eslingen (Wurtemberg). Then in 1845 another chromolithographical map by Major Heinrich Bach, representing the geology of Wurtemberg, appeared also at Stuttgart. All these maps, as well as those that followed, show great defects, both on account of lack of clearness in the colors, all being too dark, and bad registration.

Chromolithographic geological maps appeared in Berlin and in Vienna in 1851, in the "Zeitschrift der deutschen geologischen Gesellschaft" and in the "Jahrbuch der k. k. geol. Reichsanstalt." In 1853 in Switzerland, at Winterthur, J. Wurster & Cie. chromolithographed the "Carte géologique de la Suisse," by B. Studer and A. Escher de la Linth. Several of the shades in this map were put on by hand, so that it was a sort of hybrid between the two systems.

In 1854, Justus Perthes, in Gotha, published a very well executed chromolithographical map, "Geognostische Karte des Thüringer Waldes," by H. Credner, lithographed by C. Hellfarth; and, in the same year, a map also very well executed, "Geognostische Karte von Kurhessen, by A. Schwarzenberg and H. Reusse, lithographed by C. Kegel, of Cassel. The last one, especially, is a success, the coloring being but little inferior to that of the geological map of France of 1853.

In America the systems of color-printing replaced but slowly the hand processes. The late A. Sonrel, the well-known draftsman of Louis Á gassiz, tried a system analogous to that of Major Le Blanc, and in 1853 he successfully executed a little geological map, which appeared in a pub. lic document of the Commonwealth of Massachusetts, entitled: "Report on certain points in the geology of Massachusetts," by Edward Hitchcock. The map has no title, date, or place of publication, and no name of the engraver or printer. It embraces the coal field of Bristol County and of Rhode Island.

Sonrel's system consisted in cutting slips of card-board to correspond exactly with each color. These were then accurately glued to a wooden base and color applied to them by a printer's cylinder. An impression from them was then taken by a lithographic press.

In 1855 J. H. Colton & Co., of New York, engraved and printed in colors the "Geological map of the State of Alabama," accompanying the "Second biennial report of the geology of Alabama", which did not appear until in 1858, owing to the death of M. Tuomey, State geologist. Messrs. Colton & Co. also engraved and printed in colors the numerous maps of Oscar M. Lieber, geologist of South Carolina from 1856 to 1860. About 1868, thanks to the celebrated cartographical house of Julius Bien, of New York, chromolithography at last came into general use in the United States for coloring geological maps. Several of the maps made by Bien are irreproachably executed and compare favorably with those made at Vienna, Munich, Berlin, Paris, London, and Bruxelles. During the civil war in the United States there was a great falling off in the publication of geological maps on that portion of America. But shortly after its termination, a new impulse of unprecedented strength, caused not only the resumption of interrupted works, but also the birth of many new ones. The Federal Government took the lead by causing the exploration of a part of the immense territories of the West. Excellent results have already been obtained, and the important geological atlases published during the last few years under the direction of Messrs. Clarence King, F. V. Hayden, J. W. Powell, and George M. Wheeler, are an honor to the Government of the United States, and to the geologists who constructed them. The States of Michigan, Wisconsin, Ohio, Missouri, New Hampshire, and Pennsylvania have also published large geological atlases, well executed in chromolithography. • The Dominion of Canada has continued with improved success its publication of geological maps of the British Possessions in North America. Finally, British Guiana, Brazil, the Argentine Republic, and Chili have undertaken geological surveys, which, in the last twenty years, have largely augmented our knowledge of the geology of South America. The geological map of Chili, in thirteen sheets, by Pissis, published chromolithographically in Paris, compares favorably with any atlas published in North America.

Geological mapping in this country was greatly improved between 1862 and 1881, without, however, attaining that degree of perfection reached by the old and very detailed geological surveys of England, France, Switzerland, Belgium, Austria, Prussia, or Scandinavia. Although the latest geological publications on America are very superior to those which preceded them, there has not been executed a geological survey of any large area that is really final, or that leaves but little to be corrected in the future. With limited exceptions, all are geological reconnaissances, which still demand many years of work to transform them into definite and completed studies. However,

what exists already is enormous in importance and in extent, when we consider the immense stretch of land explored, from the Arctic to the Antarctic regions.

In judging the results obtained by the efforts of, after all, a rather small band of field geologists, we must not lose sight of the fact that America occupies a hemisphere, and that, compared with the Old World, the New is better known geologically, and has far less blank space on a general geological map than Asia, Africa, or Australia.

In looking over this catalogue, one will often be struck by certain peculiarities in the maps cited. Some are anonymous, others have no titles, some have no date, others have no scale, or a scale which has to be figured out to understand it exactly; in this case we have not cited the scale. Often no place of publication is given; even whole geological atlases are without such designation. Very often the date on the map does not correspond to the date of the book or memoir which describes it; in which case I have mentioned both dates, first that of the map and then that of the book. Finally, I have had to eliminate a certain number of maps called geological in their titles, which really have nothing geological about them. I have also neglected citing very small maps reduced from larger ones, which authors of elementary books have inserted in their texts in black engravings or wood cuts; for they are all reproductions-often very poor ones-of maps made by original observers, whose names are neither on these maps nor in the texts. They are merely for the use of the general public and student, and are without value in the history of science. Unfortunately no kind of publication offers greater temptations for appropriating the work of others without proper credit, than a geological map. It is offered in excuse that the knowledge belongs to the public, but geologists who respect the property of their fellow-workers, and who know that often the only recompense of very difficult work, without any pecuniary remuneration whatever, is the reputation derived from it, do not fail to cite the name or the names of the first explorers or investigators, either on the maps or in the explanatory text, or in both. Too often this simple rule of justice is violated, and numerous acts of real scientific piracy exist in geological cartography. The persons most often guilty of it are mining engineers, geographers, and travelers. Thus, one often finds in the narrative of a voyage, or in mining magazines, large geological maps, well colored and tolerably exact, with the name of an author wholly unknown in geology. If these maps are compared with those of the geologists who have made a study of the countries represented, it is surprising to find that they are exact copies, so exact indeed that they repeat faults known only to their authors. In this case the evil is not great, for every one rectifies the error and places the name of the true author in the place of that of the unscrupulous compiler. But it is not the same thing when the author of the compilation is a known geologist. It then becomes very difficult to know what really

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