Without regard to this, however, it is self-evident that such exhibits are of little value without absolute knowledge that the pinion was not improperly treated, or subjected to unusual wear. Gears and pinions have been in use in Europe and in the United States for a number of years and have shown no perceptible deterioration, excepting where an accident occurred or some foreign material was allowed to enter the gear case.

Notes and Comments.

THE PANAMA CANAL.

Although it is usually a good proposition to get the best, the principle may not apply with regard to the d'gging of the Panama Canal. Chief Engineer Wallace strongly favors its construction at sea level, and advances cogent arguments in support of his opinion. He has advised the House Committee on Interstate and Foreign Commerce that a canal so constructed would be less expensive to maintain, less expensive to operate, would save time in passing through it, and could be widened and deepened when required without interfering with traffic. All these are very good reasons, indeed, why a sea level canal should be dug rather than one with a portion of its channel 90 feet higher, requiring the use of locks. But, unfortunately, there are other considerations. Taking as a basis the estimate of the former Canal Committee, that the 90-foot level canal would require ten years for its completion and would cost $200,000,000, he figures that a sea level canal could be opened in fifteen years and completed in twenty years, and would cost $300,000,000. The increased cost will propably not strike the American people as a formidable objection to the adoption of a level which will have so many advantages over one requiring locks, although an extra $100,000,000 is no trifling matter to be lightly considered. The most serious point brought out is the greatly extended time required.

Mr. Wallace bases his estimate on a previous estimate, and both may be much out of the way. Difficulties greater than have thus far been conjectured may develop as the work proceeds, and its completion even at a 90-foot level might be delayed considerably beyond ten years. The attempt

to dig a sea level canal might be prolonged far beyond fifteen years until the canal could be opened to vessels of light draft, and it might be twentyfive years until the largest vessels could safely venture through. Those who have been most earnest in their support of the Panama Canal have, of course, been animated either by hopes of a personal benefit or of benefit to existing commercial interests. Surely those who have labored for it in season and out of season were fairly hopeful that if undertaken it would be completed while they were sufficiently interested in mundane affairs to take some cognizance of the fact. But to defer such a hope for twenty or perhaps twenty-five years would mean that very many who are now deeply interested are merely working for the benefit of posterity. If a sea-level canal should be decided upon, it is to be hoped that the estimates of both cost and time are far out of the way, and that both can be heavily reduced. Most especially is it desired that the time can be shortened.-Iron Age.

NEW PROCESS OF COLOR PHOTOGRAPHY.

Scientists, dabblers in science and earnest amateur photographers have been trying for years to discover the secret of producing photographic prints in the colors of nature as seen upon the ground glass of the camera and as projected by the lens upon the sensitized plate. The lens views and the plate receives the picture in colors, but the negative plate is incapable of fixing anything else than form and producing that in fine gradations of light and opacity. Color negatives have been made, but have not been capable of transmitting color qualities to positives, nor have color positives been successfully made by any purely photographic principles. Good color effects are produced by superimposing photographic plates in mechanical printing processes, but hitherto there has been little success in chemical reaction upon ordinary printing paper to produce color effects.

Recently, Rudolph Isenmann, of 385 Bergen Street, Newark, N. J., has produced some most promising effects in making color photographs by purely chemical manipulation in the simplest possible manner. With ordinary printing-out paper, either gelatin, albumen or collodion surfaced, such as is sold by photographic stock houses, he claims to make prints containing blue, yellow, green and brown by merely soaking the prints as taken from the printing frames in two successive baths with a washing between the chemical immersions. The colors find their places with wonderful accuracy. The rich cerulean blue arranges itself in the sky with white cloud effect, and in the sunlit parts of the water in the foreground, while the water in the shade of the green trees takes up a greenish cast and the browns and autumnal yellows appear on the leaves and are reflected in the water in some of the pictures. The arrangement of the colors seems to be natural selection influenced entirely by the density of parts in the negatives from which the prints are made. Mr. Isenmann says that he allows the colors to work out their own progress, and never uses any effort to direct them by hand manipulation. He says, further, that the process is extremely simple and cheap. He uses no gold in toning the pictures, nor does he use hyposulphite of soda to fix them. What becomes of the free silver he does not say, but he has samples of his color work which have been made and exposed for six months, and he can see no change in the colors.

While Mr. Isenmann's results are by no means perfect, they show great advance in color photography, and give promise of still greater success. He despairs of ever reaching the reds by this process, but feels that he has secured a satisfactory end by extremely simple means.-Scientific American Supplement.

IRON AND IRON SUPPLIES.

Pennsylvania, which makes more than half the iron used in the United States, produces less than 2 per cent. of the iron ore mined. Ohio, which comes next to Pennsylvania as an iron-maker, mines less than 0.1 per cent. of the total. In both cases the ore is brought to the fuel; and this is the policy in this country. Only in Alabama are the ore and fuel found together.

THE FRANKLIN INSTITUTE

William Sellers.

When a man of pre-eminent abilities and world-wide fame as an engineer and manufacturer, whose life was spent in activities contributing to the advancement of knowledge in his chosen profession, passes away at a ripe old age—having retained to the last an active interest in his business and in public affairs—it is proper that a permanent record of his useful life should be made available for the benefit, not merely of his friends and contemporaries, but of future generations as well. Such a man in all respects was William Sellers, the former President of the Franklin Institute, to whose solicitude was due, in large measure, the preservation of the Institute at a critical period of its history and its subsequent advancement. It is eminently fitting, therefore, that a suitable tribute, in the form of a biographical notice, should appear in these pages in conformity with the resolution of the Board of Managers.

Mr. Sellers was born in Upper Darby, Delaware county, Pa., September 19, 1824; son of John and Elizabeth Sellers, grandson of John and Mary Sellers and of William and Sarah Poole, and a descendant of Samuel Sellers, who, with his brother, George, from Belper, Derbyshire, England, emigrated to this country and arrived in Philadelphia in 1682. George died unmarried. The marriage of Samuel Sellers and Anna Gibbons is the first recorded in Darby meeting of Friends. He took up a tract of land in Upper Darby, Delaware -county, under Penn's Patent. This property has remained. in possession of his descendants to the present generation, and on a portion of it is the house in which the parents of William Sellers resided when he was born. His ancestors have had a long and memorable connection with science. From the organization of the American Philosophical Society some one of his family has always been a member of it. His paternal grandfather, John Sellers, then a member of Assembly of Pennsylvania, was appointed by this society in con