SCIENTIFIC AND USEFUL.

New Zealand Graphic, Volume IX, Issue 35, 27 August 1892, Page 854

SCIENTIFIC AND USEFUL.

ORNAMENTAL LEATHER WORK. An excellent imitation of carved oak, suitable for frames, boxes, vases, and ornaments in endless variety, may be made of a description of leather called basil. The art consists in simply cutting out this material in imitation of natural objects, and in impressing upon it by simple tools, either with or without the aid of heat, such marks and characteristics as are necessary to the imitation. The rules given with regard to the imitation of leaves and flowers apply to ornamental leathei work. Begin with a simple object, and proceed by degrees to those that are more complicated. Cut out an ivy or an oak leaf, and impress the veins upon it; then arrange these in groups, and affix them to frames, or otherwise. The tools required are ivory or steel points of various sizes, punches, and tin shapes, such as are used for confectionery. The points may be made out of the handles of old tooth-brushes. Before cutting out the leaves the leather should be well soaked in water, until it is quite pliable. When dry, it will retain the artistic shape. Leaves and stems are fastened together by means of liquid glue, and varnished with any of the drying varnishes, or with sealing-wax dissolved to a suitable consistency in spirits of wine. Wire, cork, gutta-percha, bits of stems of trees, etc., may severally be used to aid in the formation of groups of buds, flowers, seed-vessels, etc. NEW METHOD OF STOPPING ELECTRIC LOCOMOTIVES. In electric tramway and railway practice it has hitherto been the custom to reverse the current in order to stop the car quickly. The result is a considerable waste, and has a tendency to burn out the armature. With a view to overcome the difficulty, Mr 8. H. Short, a well-known electrical engineer of Cleveland, Ohio, has devised a new method. By means of this arrangement the motors aie disconnected from the ordinary supply wire, and are connected in a local circuit with each other iu such a manner that the current produced in thelocal circuit and acting on a motor tends tocheck the forward movementof the car. The two motorsof acar are connected in the local circuit, so that the electro motive force of each under the rotation imparted by the forward movement of the car opposes that of the other, and tends to produce a current in such a direction as to increase its own held magnetism and cut down that of the other. Thus the car will oe checked or brought to a sudden stop if running rapidly, and if on a heavy gradient will creep slowly down without taking current from the supply wire and without having the brakes set. In effecting tins, one motor overpowers the other, owing to the difference in the residual magnetism of their fields, and reverses the field polarity of the weaker motor, which is thereupon operated in such a direction as to run the car backwaid by the current from the more powerful motor, acting as a generator.

LEECH BAROMETER. Take an eight ounce phial, and put in it three gills of water, and place in it a healthy leech, changing the water in summer once a week, and in winter once in a fortnight, and it will most accurately prognosticate the weather. If the weather is to be fine, the leech lies motionless at the bottom of the glass, and coiled together in a spiral form ; if rain may be expected, it will creep up to the top of its lodgings, and remain there till the weather is settled ; if we are to have wind, it will move through its habitation with amazing swiftness, and seldom goes to rest till it begins to blow hard ; if a remai kable storm of thunder and rain is to succeed, it will lodge for some days before almost continually out of the water, and discover great uneasiness in violent throes and convulsive-like motions ; in frost as in clear summer-like weather it lies constantly at the bottom ; and in snow as in rainy weather it pitches its dwelling in the very mouth of the phial. The top should be covered over with a piece of muslin. NEW OFFICE RULER. A new office ruler has been devised by Mr Jno. Somerville, Joppa, Midlothian. It has been designed to obviate the awkwardness, uncertainty, and blotting propensity associated with the operation of ruling. The ruler itself is made of brass, and secured within it, but capable of freely revolving, are two thin cylinders of vulcanised india-rubber. The pen in ruling is guided along a perfectly true metallic surface. Hence the following advantages are claimed : The ruler does not require the hand holding it to move with or touch the revolving surface ; by providing a ruling surface not in contact with the paper, inking or blotting of paper is made impossible ; its double gripping action on paper effectually prevents slipping or getting out of position ; its capacity for resting on a sloping surface, a feature at once unique and of great utility ; the ease and rapidity with which it can be used, and the consequent saving of time effected ; being made of metal, it will not warp, and is specially adapted for hot climates. SUNSHINE IN ENGLAND. Sunshine is recorded at the Meteorological Office in England by means of the Stokes Campbell instrument, the essential feature of which is a spherical lens, which acts as a burning glass. As the sun accomplishes its apparent journey from east to west it burns its autograph into a strip of card placed beneath the lens, but can only do so when it is unobscured. As the card is divided into hours it is easy to calculate the amount of actual sunshine with which each day is favoured. A report has recently been issued giving the results achieved by this instrument for the past ten years. From this we learn that the Southern coasts are the most sunny ones, if we except the Channel Islands, as repiesented by Jersey, where alone one-half the possible amount of radiance was registered for May and August. The east coast of Britain is also decidedly sunny. In the summer and earlv autumn Ireland shares with the west coast of Scotland the reputation of persistently clouded skies, but later on toward November the observatory in Phmnix Park, Dublin, records the greatest average amount of sunshine for that month — namely, 28 percent. In the metropolis, as might be expected, the record is bad, the sun failing to leave any trace on the card for more than one entire month.