The size of the Atlantic waves has been carefully measured for the Washington Hydrographic Bureau. In height the waves usually average about 30 ft., but in rough weathertheyattain from40to48ft. In storms they are often 500 to 600 ft. long, and last 10 or 11 seconds, while the longest yet known measured half a mile, and did not spend itself for 23 seconds.

An interesting correspondence, says the London "Electrical Review," has been proceeding for some time in the "Chemiker Zeitung" on the cause of the occasional explosions of vapors which have taken place at different chemical works. A very inflammable volatile liquid, carbon bisulphide, more particularly, has been run through metallic pipes, or through a metallic funnel, into a metallic or non-metallic drum, replacing the air formerly in that vessel. Part of the liquid has evaporated, forming a mixture of vapor and air, which, in the total absence of fire or artificial light, has exploded and done more or less damage. It has been so difficult to find the proper explanation for this curious phenomenon, that certain writers have suggested that the friction of the passing liquid upon the edges of the funnel or the mouth of the pipe must have generated sufficient electricity to produce a spark, which has immediately fired the explosive mixture.

A more probable and entirely chemical explanation of the explosions has now been put forward, which appears to meet all the requirements of the case. According to this view, when a volatile organic liquid of the kind now under consideration, which contains sulphur either as a part of its nature, or as an impurity, is brought into contact with iron or steel, sulphide of iron is formed. In presence of air this body oxidizes, generating so much heat in the process as to raise the mixture of vapor and air above its inflaming point, when, if it takes fire in a confined situation, it prod-duces the symptoms of a gas explosion.

Stone sawing by wire is done successfully in France, according to a paper by Mr. E. Bourdon in the "Bulletin " of the Society for Encouragement of National Industry. A complete plant comprises an endless wire passing around a series of pulleys, one of which is a driving-pulley. The necessary tension is obtained by a straining trolley working on an inclined plane, and between the driving shaft and this trolley is situated the saw frame, which carries the guide pulleys for the wire saw. This wire, which is driven at a given speed, is caused to press lightly on the stone, and the cutting is done by sand mixed with water, which is conveyed into the saw cut as the work proceeds. Though the mode of operation appears simple, it entails various difficulties in practical application. Three twisted steel wires are used, each wire having a diameter of 0.098 in. The strands must be twisted fairly tight, and should make one turn in 1.18 in. The wire may be driven in the workshop at a speed of 23 ft. per second, but in quariies, drifts and mine tunnels the speed should not exceed 13 ft. per second. The force exerted by the wire to produce the cut must be uniform and must be capable of being readily varied. Moreover, it must be proportionate to the length of the cut.

Carbon and metal brushes for dynamos have their advantages summed up in "Technics," according to which a most important departure in dynamo design was made when carbon brushes were introduced. With metal brushes sparking can only be avoided by altering their lead, with every variation of load. When carbon brushes are used, and the dynamo has been suitably designed, absolutely sparkless running may be secured for all loads with fixed brushes. It is, perhaps, not too much to say that the present success in the design and construction of large traction generators is due to the use of carbon brushes. Their superiority to metal brushes is due to several causes. In the first place, metal brushes, when greatly heated, are liable to fuse at the tips, with the result that the commutator becomes pitted. In addition, metallic vapor is sometimes produced, and this gives rise to an arc between the brush and tip and the commutator segment which has just left it. Both these sources of trouble are removed when carbon brushes are used. In addition, there is a definite contact resistance between a carbon brush and the commutator segment on which it rests, and this resistance increases as the commutator segment is withdrawn from under the brush. The effect of this is that the current in the armature coil, short-circuited by the brush, is first reduced to zero, and then reversed, without any help from a reversing field. The method of commutation with movable brushes may be compared with the method of stopping a locomotive by reversing the engine, while the use of fixed carbon brushes for commutation may be compared with the use of a brake.

The waste of gold in a manufacturing jeweller's premises is likely to be so considerable that the most stringent measures have to be taken to avoid loss by reason of the gold dust falling to the floor, getting caught in the workers' clothes, getting washed off his hands, and so passed to the drains, and in many other ways. An American jewellery trade paper says that some time ago a gold and silver manufacturing firm had occasion to put in a new floor in its work room, and the man who made the change simply took the old floor in payment of his work, and was well paid. In the process of manufacture it is impossible to avoid small particles of the precious metal flying upon the floor, where they are trodden into the crevices until the floor is saturated with them. The floor in a manufacturing jeweller's workshop, which has become so worn that it must be replaced, contains fully sufficient gold to pay for a new one. The shop sweepings are sent to the refiners' for the gold to be extracted. The process of extracting the gold from these sweepings is very simple. They are burnt, and the ashes are carefully collected; the buyer selects samples here and there, taking a portion from every part of the heap. These he weighs, puts through a grinder and sieve, then thoroughly mixes the product, takes a sample of it, weighs it, refines it and calculates how much gold there is in the whole quantity of ashes. From this he forms an estimate of the value and pays accordingly. Even the water in which the gold is washed when a ring or other article of jewelry is to be cleaned is preserved until there is sufficient quantity to make it worth while to separate the gold from it.

M. Positano, of Rome, has recently succeeded in making a modification of the well-known Daniell cell, increasing the electromotive force and intensity of the battery, without diminishing its constancy. M. Posi-tano substitutes for the ordinary exciting element (water containing a certain percentage of sulphuric acid) a solution of chloride of ammonia of 25 per cent, strength; also, to increase the intensity, he replaces the hollow cylinder of copper by a spiral formed of several turns of strip copper. The pile, as modified, gives a current relatively intense, and the cell will find a new use in galvanic applications, and for electric clock service, as well as in telegraphic and other work where a constant current of small intensity is required.

" Pearl solder " is the misleading name applied to a very fusible solder employed for repairing articles containing pearls and other gems, when it is inconvenient to remove these. The color of pearls is easily destroyed by the heat essential to hard soldering, and so a special solder of low fusibility is necessary. Such a solder-may be prepared as follows: Bismuth, 1 pwt. (.050 part); lead, 15 gr. (.031 part); tin, 9 gr. (019 part). This solder melts at about the boiling point of water, and is useful for many intricate little jobs. The flux used is venice turpentine, which does not leave a stain on the finished work if the heating is done with care.

Aluminum silver or silver metal is an alloy of copper, 57 parts; nickel, 20 parts; zinc,20 parts, and aluminum, 3 parts; and it is coming into use for typewriter spacing levers. It is njckel-plated when the machine is new, but as the nickel wears off the metal still remains of a silver white color, which will not tarnish or rust. This metal is conceded to be better than brass, steel or iron for this special purpose; it is stiff and strong, does not cost more than brass, and is sufficiently hard to take a high polish.

It is said that radium has the property of completely neutralizing the poison of the viper, on fifty to sixty hours exposure.