The size of the eclipse will be the same for all places. The time of middle and end for any other places may be obtained by applying the difference of longitude from Washington, converted into time, to the Washington time of middle and end, adding if east of Washington, and subtracting if west.

[ An Interesting Astronomical Observation.]

To the Editor of the Scientific American:

While viewing the planet Jupiter, at about 5 minutes past 10 o'clock P.M., a very strange sight presented itself to the observers, who were looking for a transit of one of the satellites. A very dark spot much larger than a satellite was seen on the eastern edge of the disk, as shown in the above diagram. It moved rapidly westward along the upper margin of the northern belt and passed off at 1 o'clock 24 minutes A.M. (12th). From its first internal contact till its last external contact was just 3h. 19m., Pittsburg time. It appeared to be a solid opaque body, truly spherical, very sharply defined, and most intensely black. The transit of the satellite occurred at 15 minutes after 11 o'clock, and had no unusual appearance. Now what was that dark body? We are constant observers of the heavenly bodies, though not deeply versed in the science of astronomy, and are anxious to know if any one can give us some light on the subject. The telescopes used were a 2½ inch and 5 inch achromatic, magnifying 154 and 216 diameters, but the 154 was chiefly used. was chiefly used.
Joseph Wampler.
James R. Gemmill.
McKeesport, Pa., July 11, 1878.

[ Some of Professor Marsh's Recent Discoveries.]

Mr. S. W. Williston, the assistant of Professor Marsh, has been giving to the Omaha Bee some interesting facts with regard to the great reptilian fossils recently discovered in Wyoming and Colorado. The bones found represent reptiles of many sizes, from that of a cat up to one sixty feet high. The latter, found at Como, Wyoming, belonged to the crocodile order; but the remains give evidence that the animal stood up on its hind legs, like a kangaroo. Another found in Colorado is estimated by Professor Marsh to have been 100 feet long. A great many remains of the same general class, but belonging to different species, have been collected and sent East. Among them from three to four hundred specimens of the dinosaur, and about a thousand pterodactyls, have been shipped from Colorado, Wyoming, and Kansas. The wings of one of the latter were from thirty to forty feet from tip to tip. Seventeen different species of these flying dragons have been found in the chalk of western Kansas. There have also been found six species of toothed birds. Comparatively little has been done toward classifying the late finds, the task is such an enormous one. Great importance is attached to them, however, since nothing of the kind had been found in America until a little over a year ago and great stress had been laid by certain geologists on their absence. Another remarkable feature of the discovery was that the fossils which had been reported as not existing in this country had hardly been brought to light in one locality before thousands of tons of them were simultaneously discovered in half a dozen different places.