FOR many years the New York Fire Department has maintained a training school for firemen where practical instruction was given to those who had passed the civil service tests and had been appointed for a probationary period of one month. This training school not only was indispensable for the New York Fire Department, but served as a model for those of many other cities. To-day the need of thoroughly trained firemen is greater than ever, and their education can not be confined to such rudiments and essentials as may be taught to the probationer, but in addition must involve systematic instruction all along the line up to and including the officers in command of companies and battalions. In efforts made recently to raise even higher the standards of the New York Fire Department there has been established a Fire College which includes not only the various schools previously maintained by the department, but aims to extend and systematize the instruction in practical fire-fighting, especially in the use of motor apparatus and other modern appliances now so extensively employed. This instruction is given by the best qualified men in the department and promotions to higher grades so far as is practicable are made only from those who have satisfactorily completed the appointed courses. The chief of the department is the head of the Fire College Board, and the college itself is composed of a probationary firemens school, engineers school, officers school, company school, and a special class in automobile operation. The first of these to be organized was the Probationary Firemens School, at which all the probationary firemen are required to attend for at least thirty days after their appointment and before they are regularly accepted and permanently detailed to companies. The instruction here as the illustrations show is exclusively practical, being based upon that formerly in vogue in the training school, but amplified as regards its amount and in the apparatus used. The practical work takes place, in the rear of Fire Headquarters, where the probationers are marshaled with their scaling ladders of hardwood surmounted by a toothed hook and containing cross pieces up which a fireman may climb after the hook driven through a pane of glass perhaps is firmly placed on a window sill above. A number of scaling ladders in the hands of the firemen trained to their use affords a ready means of climbing up the side of a building and of passing from window to window. The probationers are taught not only the use of the scaling ladder, but to climb ladders of all forms used In fire fighting, to raise and lower them, to straddle and stand on window sills, holding perhaps a companion in* search of a point of vantage, or passing along some inmate of the house who has been overcome by smoke. The large ladders, some of them 50 feet in length and carried on the hook and ladder trucks, also are used in the school, and the life saving rope which is shot up to the roof by means of a gun and shot line. The firemen are taught to haul up hose and ladders by a rope^ and to lower persons to points of safety when stairways and fire escapes are cut off by the flames or smoke. This means that the firemen must know the various knots employed and the method of using the gun. Then there is the use of the life net, for perhaps no one is left on the roof to lower the fireman and he must learn to jump properly' into the net held by his comrades. They, too, must know how to hold the net properly. All of 'this involves careful training for the muscular men who already have passed a severe physical test, and day after day they raise ladders, climb up and down them to the top of the six stories of Fire Headquarters until they become expert. Then also they must learn the use of the hooks and axes for getting directly at the seat of a fire and removing smoldering wood, the use of picks, battering rams, crowbars, mauls, door openers, lock openers, tin roof cutters, wire cutters, and pinch cutters, all to get into a building or directly at the flames, for a fire may occur at night when a building is tightly locked. Furthermore there are the ordinary connections of hose; to make them speedily is one of the first duties of the fireman, and he must understand the making of Siamese connections, taking a line from engine or high pressure hydrant to a stand-pipe, carrying hose into buildings, and up ladders, connecting with a cellar pipe, and finally the use of hose within tall buildings where the building pumps or the city high pressure may force water far above the limits of the fire-engine in the street below. The high pressure now used in the lower parts of New York city presents many problems and dangers for the hosemen, and this is a modern feature which the new system of instruction aims to make clear. The construction and use of the large special hydrants and reducing valves is demonstrated and the method of connecting hose thereto and, the use of the nozzle holder are explained. There is also instruction in the use of the fire alarm telegraph system so that various alarms, ambulance calls, and other signals can be sent, and finally the Fire Department surgeons give an elemental but practical course in first aid to the injured. Interesting and important as this work is, it is perhaps exceeded in actual usefulness so far as the New York Department is concerned by other schools for the engineers and higher officers. Thus in the past there has been criticism of the engineers of the fire department that in some cases they did not keep their engines at a high degree of efficiency, and in actual operation they did not get the results that a more.inti-mate and intelligent knowledge of the machinery would have secured. Accordingly a few years ago an Engineers' School was started with beneficial results, and this was made a part of the Fire College with a more extended course and competent instructors. In the high pressure districts the engineer of a company' is stationed at the hydrant watching the control and reducing valves, while with the extensive introduction of motor apparatus now in progress he will be concerned with the care and operation of the gasoline engines. In the first place all engineers are required to attend this school, which is open also to first and second grade firemen upon approved application. Hereafter only graduates of the school will , be appointed as engineers. The practical work is being done in one of the machine shops of the department and consists of an extended course in engines and boilers and gasoline motor engineering. Here the engineers and firemen desirous of promotion study the actual machines and their construction and operation. For many of the engineers, not to mention the firemen, gasoline motors have been a sealed book, but under the administration of Commissioner Johnson much motor apparatus is being added to the New York Fire Department and eventually the entire department will be on a motor basis, so the importance of the work is evident. In fact so immediate is the demand for properly qualified chauffeurs belonging to the uniformed force and men competent to operate and repair gasoline engines, that there has been established a special class at the repair shops of the department for the training of such firemen. Here the men are taught the practical operation of motor apparatus so that competent chauffeurs will be forthcoming as the horse-drawn apparatus is displaced. This is taking place as rapidly as possible, and by the end of the year the New York Fire Department will have a number of distinct and separate types of motor-drawn machines in use. The Officers' School affords a means of raising the general technical standard by having those who have evolved certain practical methods teach them to others, and give general information as to conditions and methods in different parts of the city. Thus chiefs and company commanders in the high pressure districts have learned to use this new weapon most effectively and gradually are standardizing the different practices. These must be taught not only to those serving in the protected territory but to others who may be called there either individually or with their companies in the event of a large fire. In other words, certain chiefs and firemen have acquired special skill in dealing with certain conditions, and it is the intention that such methods should be taught to every officer. For the company school entire companies are ordered to Fire Headquarters and are instructed and drilled in the effective use of the apparatus. The entire Fire College is intensely practical in its spirit, and its object of raising the general standard of fire work in New York city doubtless will be attained. With the practical work thus brought up to an even higher degree of excellence, it is likely that problems of construction and engineering eventually will be undertaken and the technical and professional knowledge of the firemen be correspondingly broadened, but to-day it is realized that efficiency alone is the keynote and this can be realized only through training and discipline. Wireless Detectors By Adelbert J. Gogel ELECTRIC wave detectors, the most delicate part of the wireless receiving set, are the subject of much argument as to their relative sensitiveness and relative merits. There are a number of different types known, which may be arranged as follows in order of merit, according to most authorities: (1) Electrolytic; (2) Peroxide of Lead; (3) Perikon (Chalco-pyrites and zincite); (4) Ferron (Iron pyrites); (5) Silicon; (6) Molybdenite (Molybdenum Disulphide); (7) Galena (Lead Sulphide); (8) Carborundum (Artificial Silicon Carbide) . The Electrolytic Detector, perhaps the most widely known type, appears in many forms, the most frequently used of which is that in which the point of a very fine silver plated platinum wire, about 0.001 millimeter in diameter, called a Wollaston wire, is immersed in a nitric acid solution contained in a small graphite-carbon cup. It is necessary to use a battery and a non-inductive rheostat capable of very fine adjustment, called a potentiometer, in connection with this detector. The battery polarizes the electrolytic cell, that is, the fine platinum wire is. covered with tiny bubbles of oxygen and then the resistance rises so high that the current is nearly reduced to zero. If then an electric wave fall on the aerial connected to the electrolytic detector, it suddenly reduces the resistance of the cell. A telephone receiver of great sensitiveness being connected in series with the cell and potentiometer, sound signals can be heard in the telephone. For general and long distance work, this detector cannot be excelled except in localities where high powered interference is very frequent, which causes the platinum wire to be dissolved very rapidly and a detector working on different principles must be substituted. Substitutes will be mentioned later. The Lead Peroxide Detector consists essentially of a pellet of lead peroxide clamped between two surfaces, one of lead and one of platinum. A battery, potentiometer and telephone receiver are connected with the detector in the same manner as with the electrolytic detector. The lead peroxide detector works on a new principle; although no acids or liquids of any kind are employed, its action is electrolytic. When lead peroxide, lead and platinum are brought in contact as described, it has long been known that lead will be deposited on the platinum surface. When a battery is connected up properly with the detector, it opposes this action and causes the lead to be deposited upon the lead surface. When an electric wave falls upon the wires connected with the detector, a sound in the telephone is heard because of the change of resistance brought about by the passing of a wave. The Perikon Detector contact is between crystals of chalco-pyrites and zincite; in the Ferron Detector between a crystal of iron pyrites and a metal point; in the Silicon Detector between the element silicon and a wire; in the Molybdenite Detector between a crystal of molybdenum disulphide and a metallic surface; in the Galena detector between a-crystal of lead sulphide and a very fine wire; in the Carborundum Detector between a crystal of carborundum or silicon carbide and a metallic surface. The Silicon Detector retains its adjustment even when very near to a very high powered sending apparatus, and is therefore to be recommended where interference is very severe. If a piece of 99/100 per cent pure silicon can be procured, nothing better can be desired. The Carborundum Detector, even though subjected to somewhat severe blows, often retains its adjustment for' months at a time, which ca uses it to be the favorite detector with the amateur. However, it requires the use of a battery and potentiometer for its efficient use in long distance work. The green crystals are more sensitive than the blue or purple ones. The side of the crystal connected to the ground should be covered with tin foil or soldered in a cup. A New York firm has put on the market a promising new detector for which broad claims are made. This detector is of the vacuum bulb type and very similar to the “Audion” of Dr. Lee De Forest, which is not within the reach of the average experimentalist owing to its high cost. This detector consists of an electric light filament, a grid and a plate sealed in a highly exhausted bulb. A battery to light the filament and another battery and a rheostat capable of very fine adjustment are necessary for the operation of this detector. When the current to light the filament is turned on, the detector is ready for business, requiring no adjustments of crystals and points or Wollaston wire and acid. This detector can be used to receive from all systems of transmission; singing spark, quenched spark, arc sets, telephone sets, in fact it will detect any wireless wave from whatever source it is produced. The makers of this detector claim it to be more sensitive than the electrolytic, which will be a decided advance in wireless receiving apparatus. The wireless operator should not content himself with one detector, but should have several ready for use and a switch with which to connect up t.he desired one. A device of some kind should be used to ascertain whether or not the. detector of a wireless set is in a receptive condition. Several devices of this class are quite well known, but a short description will not be amiss. If a key sounder and battery are connected up neilr the detector, a sound is heard in the detector when the key is raised, if the detector is in working order. This method requires the constant operation of the key during the test or search for a sensitive area. But the author has found that if an ordinary electric bell with the gong removed, or a buzzer, is connected with a switch and battery, and two or three feet of copper wire be connected to the interpreter, the arrangement is .much more convenient and efficient. The short length of wire acts as an antenna, and owing to the speed of the vibrator, a continuous musical note is heard in the receiver when the detector is working properly. A variable condenser of good capacity should be shunted around the detector, enabling weak signals to be strengthened or cut out as desired. While transmitting, the detector should be short circuited by a switch to prevent its being burned out, or the wire in the telephone fused. When not in use, the detector should be protected from dust and moisture. The crystals of the thermo-electric type of detector should be touched with the hands as little as possible, for the oil secreted from the skin causes a marked decrease in the sensitiveness.