over smooth, hard-surfaced roads. By this action the bicycle-riders show a readiness to do their share toward securing improvements that are important to all users of roads. Competitors' blanks and particulars will be sent by Isaac B. Potter, 278 Potter Building, New York, or Charles L. Burdette, Hartford, Conn. The competition closes May 1, 1891.
New Metric Standards.—Prof. Mendenhall exhibited at the last meeting of the American Association exact copies of the new metric standards received by the United States Government from the International Board of Weights and Measures. The standards, when received, were opened formally in the presence of the President and Secretaries of State and the Treasury and sixteen specially invited scientific men, and duly certified to, as was done with the standard troy pound during the administration of John Quincy Adams in 1828. The meter is a rod with H cross-section, made of an alloy of platinum and iridium. In making these standards for the various governments, two thirds of all the iridium known in the world was used. The extreme delicacy and exactness of the measurement work done upon the standards was illustrated by saying that when two of the standard kilogrammes were balanced against two similar masses, if one of the masses on one side of the balance was placed on top of the other mass, the balance would be destroyed. In other words, raising the mass of one kilogramme through less than two inches made a difference in the attraction of the earth readily observed.
Some North Dakota Mounds.—Mr. Henry Montgomery, between 1883 and 1889, excavated and explored thirty-nine ancient artificial mounds in North Dakota. They consisted of one beacon mound, one well-marked sacrificial mound and another not so well marked, and thirty-six burial mounds. The burial mounds were of two kinds. The ordinary burial mound consisted of a circular, rounded, or conical heap of earth, mostly rich, black soil from the prairie, clothed with grass, and rising generally to a height of several feet above the surrounding level. One or more vaults occur in each, in which human skeletons and various implements, ornaments, trinkets, etc., are found. A single vault is near the center; two or more vaults are found eccentric in situation, and at varying distances from one another. The vault is a circular, well-like pit, having a calcareous bottom and wall, and often also a calcareous covering. In digging for the vault which was done systematically, a foot at a time, the level being carefully preserved—wood was found at the depth of about a foot, consisting of poles or young trees, varying in diameter from three to ten inches, charred at their ends and over the greater part of their surfaces. The skeleton was generally found in a crouching posture, with back against the wall and face toward the center. The second kind of burial mound is distinguished by having no wood and no burial chambers, and in the bones being broken and scattered. A third kind of mound, containing a layer of clay that seems to overlie many human skeletons, is hardly distinctly enough defined to be constituted a separate class. A well-defined sacrificial mound was explored by the author on the south side of Devil's Lake. Another mound, somewhat resembling this, was opened near Sweetwater Lake in July, 1889. A beacon mound in Beacon County was explored in September, 188*7. The mounds are situated on high ridges and hills, composed often of drift clays and bowlders, and sometimes of gravel and sands.
Prehistoric Traps.—Some curious wooden machines fished up from European peatbogs were described by Dr. Robert Munro, in the British Association, as probably prehistoric otter and beaver traps. Two of them, which were taken as typical, were found in the great Laybach Moor, in the vicinity of the famous group of lake-dwellings there under investigation. The more perfect of the two was made of a solid piece of oak thirty-two inches long, twelve inches wide, and four inches thick. It tapered a little at both ends, and contained a rectangular hole in the middle, nine inches long and five inches wide, for a valve, which was worked by pivots projecting into corresponding holes in the framework. The valves were freely movable when pushed upward, but the motion was arrested a little short of the perpendicular by the slanting shape of their