Many unsuccessful attempts have been made to design a practical automatic track for use on traction enginps, whereby the latter could be made to serve all the requirements of the farmer, but. apart from their being generally too cumbersome, it has frequently been found difficult to turn the engine around or make a curve within a reasonable space. The illustration represents an improved track-laying device, which has been patented by Edward Ingleton. of the Ingleton Steam Plow Company, of Pottstown, Pa., for use on tractiou engines. The illustration shows the appliance both in and out of operation. The track is pivoted to the main Inlp of the engine, and is so fitted that it can rise or fall without altering its length. It is connected by a rod or pitman to a crank keyed on each end of the steerage roller, so that the vertical movements of the track are goverlJed automatically by the steering of the engine and tbe lateral movement of the f;'Ont end of the latter. The moment the engine is steered from its straight course the cranks on the steering roller come off thp dead center, and allow the back end of the track to rise in the same proportion as the front, or steering axle, has turned. This brings the center of the weight back under the main axle, and the engine can swivel around in as short a space, and without straining the track, as if the track were not there. The appliance is designed to greatly increase the usefulness of the traction engine, from which it can be detached in a few minutes, as desired. The steering and adjusting of the track is done by Ingleton's steam steerage, not shown in the engraving. When not required in use, the cranks on the stpering roller are reversed and the track is then held dear of the road. The importance of being able to use a steam engine in all the laborious work of the farm. and thereby reduce the number of horses and men required in c'ultivation, with the attendant cost of feeding through many months when in idleness, cannot be overesti- mated. If the thousands of horse power available in traction engines that are now idle could be successfully harnessed, it would prove a most powerful auxiliary to the farmer, as such engine, fitted with a proper track, according to the design of the inventor, should be made to plow; then, by means of a suitable machine, to seed and harrow, run the self-binder at harvest, and, lastly, do the thrashing. -ll Progress oC the Panama Canal. It was announced recently that the French company in charge of the work on the Panama Canal is now collecting 2,000 more men from Jamaicaand other West Indian islands to add to the 1,800 now at work, and that it is intended eventually to increase tbe force to 6,000 men. The New York Evening Post declared that it had received information wbich it considered trustworthy that the money to finish the work on the present plan has all been furnished, and that nothing can prevent the opening of the canal at the appointed time. except accidents and obstacles not now anticipated. The managers even expeet that the work will be completed in six years. This is quite in line with the report made by Sir Henry Tyler, thelate president of the Grand Trunk Railway, who has been visiting Panama. He says that it is proposed to construct two large dams, one across the Upper Chagres River and one on the Lower Chagres River. Twolakes will thus be formed, the upper one supplying water to the higher portion of the canal, while the lower one will be mainly used to furnish water for the navigation of the lower part. Ten locks will be built, enabling the canal to reach a height of 170 feet above the sea level. Sir Henry holds that there is no insuperable difficulty in thp completion of the canal in six years, at a cost of $100,000,000 by utilizing the work already done for a distance of sixteen miles from Colon and four miles from Panama. On the other hand, MI'. Colquhoun, the correspondent of the London Times, who has recently inspectpd the route, estimates that, even supposing one-third of the work to have been concluded, it will cost more than $200,000,000 to complete the entire undertaking. He declares that the Chagres River and the Clllebra cut of tbe prpsent Panama Canal plans are insurmountable obstacles.The Outlook. - I I - Patented artificial skin is now produced in Germany. It is madp by removing the outer and inner mucous membranes of the intestines of animals and partly digesting them in a pepsin solution. The fibers are then treated with tannin and gallic acid, the result being a tisslle which can be applied to wonnds like a natural skin, and is entirely absorbed in the process of healieg. An Improved Motor Cor Sewing Machine Sewing machines adapted for useful general work are nvariably driven by a treadle to which either one or both of the feet may be applied. The ordinary treadIe answers well for the stitching of exceptionally stout materials and for the purposes of various machines driven with the foot by men such as turners or print-ers, but for average sewing machine work it has the drawback of requiring more effort than is necessary. This extra fatigue is a serious consideration in the case of females employed all day long at the machine, bllt m ingenious modification of the ordinary treadle has now been introduced by which the labor of the worker will be greatly economized without any sacrifice of ifflciency. As is well known, the ordinary treadle is horizontal when at rest and has to be forcibly depress-ed by the foot in order to turn a flywheel by means of crank. In the new system the flywheel and crank are retained, but the horizontal treadle is replaced by a vertical one which is hinged to the under side of the table on which the machine rests, and hangs down almost to the floor, where it ends in a horizontal platform for the foot. The worker's foot is not, moved up and down to drive the machine by pressing the treadlP, hut produces the same effect with less labor by a gentle swinging of the foot backward and forward. The muscles chiefly employed are the flexors and extensors of the knee joint, and the weight of the foot and leg is, of course, supported by the platform on which the foot rests. An important advantage is that the continual movement of the thigh, inevitable under the present system, is so diminished as to be hardly perceptible. The ,.Hygienic Motor" is the appropriate name of the new invention; its principle is sound and the details are extremely simple. The ordinary treadle is em-ployed to most advantage when the flywheel is comparatively heavy and the operative stands at the machinp; but for seamstresses who sit all day long at the machine the to-and-fro movement of the foot is le exhausting than the alternate upward and downward movement which has hitherto been required. The new system can be readily adapted to any of the existing kinds of sewing machine. - The Absolute Dimension of Stellar Systems. In a recent number of the Astronomiscbe Nachricbten (No, 3314) Dr. T. J. J. See has a very important paper on the " theory of the determination, by means of a single spectroscopic observation, of the absolute dimensions, masses and parallaxes of stellar systems whose orbits are known from micrometrical measurement ; with a rigorous method for testing the universality of the law of gravitation." The ordinary determination of the orbit of a double star furnish us no idea as to its distance from us, and hence no measure of the absolute dimensions or masses of the system. The measures of the parallax upon which we depend for our estimatesof distance are extremely difficult and the results arp in most cases unsatisfactory. The measures are taken from neighboring faint stars, which are assumed to be so much more distant that their annual displacement will be imperceptible. This assumption is not always safe and the resulting parallaxes can only be regarded as relative. Dr. See shows how, by a very simple and elegant method, we may determine the absolute dimensions of the orbits of bright rapidly revolving binary stars, by single spectroscopic measures of the motions in the line of sight of the component stars. From the dimensions and other known data of the orbits, the actual masses of the stars and their distances from us can be easily calculated. But the mm:t important result of this method is the llIeans it furnishes of testing the question whether the Newtonian law of gravitation applies to stellar systellJs as well as to the solar system. Dr. See shows how we may calculate the motion in the line of sight in all parts of the binary orbit. These calculations are based upon the law of gravitation and a single spectroscopic measure. If such measures be continued upon a nnmber of pairs, while th8 scats complete their revolutions and the computpd and observed motions in the line of sight agree throughout, within reasonable limits of error, it will constitute a strong proof of tbe universality of the Newtonian law.H. C. W., Popular Astronomy.