The last class in the elementary instruction is the one in escapements (Fig. 1), the programme of which includes several distinct parts: (1) The tools that are strictly necessary; (2) escapement and cylinder adjustment; (3) making the compensating balances for the pupil's pieces; (4) pivoting, putting in place, and finishing the escapements in regulating pieces. Here, as in the preceding classes, the pupils must do all the work themselves. During their stay in the elementary classes the work done is submitted to the director, who examines it and sends it back to the instructors accompanied with a bulletin containing his estimate as to its value, and his observations if there is occasion to make any. Pupils who cannot or who do not wish to go over the entire field of the programme stop here, and are now capable of earning their living and of lightening the load that oppresses their parents.--_Science et Nature_. * * * * * MACHINE FOR POLISHING BOOTS AND SHOES. The principle of an apparatus for blackening boots and shoes dates back to 1838, the epoch at which a machine of this kind was put into use at the Polytechnic School. Since then it seems that not many applications have been made of it, notwithstanding the services that a machine of this kind is capable of rendering in barracks, lyceums, hotels, etc. Mr. Audoye, an inventor, has recently taken up the question again, and has proposed to The Société d'Encouragement a model that gives a practical solution of it. The use of this will allow a notable saving in time and trouble to be effected. This brush (see engraving) revolves around a horizontal axle supported by a cast iron frame similar to that of a sewing machine. Motion is communicated to it by a double pedal, which actuates a connecting rod and a system of pulleys. The external surface of the brush contains three channels in which the foot gear to be polished is successively placed. In the first of these the dust and mud are removed, in the second the blacking is spread on, and in the third the final polish is obtained. [Illustration: MACHINE FOR POLISHING BOOTS AND SHOES.] In order to guide the blacking to that part of the brush which is to receive it, Mr. Audoye protects the lower part of the latter by a half-cylinder of sheet iron. On this there is placed a vessel containing the blacking, and into which dips a copper cylinder having a grooved surface. The horizontal axis of this cylinder is movable; when at rest it is so placed that the cylinder is an inch or so below the brush, but when the operator pulls a button that is within reach of his left hand, the axis is lifted, a contact takes place between the brush and the cylinder, and the former is thus given a rotary motion. As the cylinder still continues to dip into the blacking, the latter is thus spread ever the brush.--_La Genie Civil_. * * * * * PERSONAL SAFETY WITH THE ELECTRIC CURRENTS.