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M. Chevalier, the eminent French explorer, has recently returned from prolonged travel in Central Africa. He has secured a valuable collection of interesting documents and photographs of the country and its people. Furthermore, he carried on his travels a phonograph, upon which he has secured records of the languages of the various natives in the region which he explored, made by the natives themselves. These records will be reproduced by Mr. Chevalier in the course of his lectures describing his travels, expeli.-ences, and discoveries. A French inventor, M. Heit, has devised a new type of compass, which is automatic in its action. By means of this contrivance, the direction of the compass is automatically registered minute by minute, so that by consulting the chart which is thus produced the ships officers can ascertain the exact route traversed at any time of the passage. In . the Heit apparatus the compass card, instead of having at its center an agate resting on a fixed steel point, is fixed on a steel pivot which rests on a fixed agate. The latter is immersed in a drop of mercury, which serves to conduct the current of electricity that renders the registering of the movements of the compass possible. To perform this function, a small silver index, kept in constant electrical communication with the pivot by b fine and flexible wire, is attached to the card. Normally. this index does not touch the fixed basin surrounding the card, but by means of tl.e electrical current the circuit is rapidly closed and opened, with the result that the angle of the boat with the meridian is registered. For this purpose the basin is divided into a certain number of sections, isolated from each other and corresponding in each case to a special circuit, the registration being made on a sheet of paper by means of a spark produced by a small induction coil. The apparatus also registers the speed of the boat by recording the revolutions of the screws, at each stroLe of the piston a current being closed and a signal sent to the receiver. Mr. Percival Lowell, director of the Lowell Observatory, speaking of what constitutes satisfactory or unsatisfactory vision of the celestial bodies, says, in substance: Studies directed to that end have resulted in a knowledge of the conditions which constitute good or bad seeing. The basis of the matter lies in the well-known fact that systems of waves traverse the air, several of these systems being present at once at various levels above the earths surface. The waves composing any given system are constant in., size and differ for the different currents all the Way from a fraction of an inch to several feet in length. If the distributing wave be less from crest to ciest than the diameter of the object glass, the image is confused by unequal refraction from the differ-ent phases of the wave; if the wave be longer than this, a bodily oscillation of the whole image results. The first. is fatal to good definition, the second makes accurate micrometric measurement difficult. It is easy to make these waves visible by taking out the eyepiece and putting ones eye in the focus of the instrument when the tube is pointed at a bright light. It is further possible to measure their effect by carefully noting the character of the spurious disk and diffraction rings made by a star, and the extent of the swing of the image in the field of view. By combining the amount of confusion with the degree of bodily motion of the resulting image the definition at any time and place can be accurately and absolutely recorded. The perfection of the optical image of a star testifies to the lack of damaging currents with reference to the object glass used. It records all the waves below a certain wave length. Similarly, the amount of bodily motion registers all those above that length. The biggest carving knife ever manufactured may be seen at the Worlds Fair. This monster blade is 30 feet in length and has an edge as sharp as it razor., It is made out of the finest steel, and the handle is a masterpiece of the cutlers art, elaborately carved and beautifully polished. It would take a veritable giant to wield a knue liKe this. The blade is altogether of American manufacture, and it is expected to show for the first time that American cutlery has now reached a point of perfection where it fears no rivalry. The giant carving knife cost several thousand dollars, and special machinery had to be made before its construction could begin. No such knife was ever before manufactured.
