194 



THE INDIA RUBBER WORLD 



[January 1, 1917. 



to each operator and wlieti any one of these is operated, the 

 clutch opens, disconnecting the rolls from the motor, and the 

 brake is applied to the rolls, stopping them almost instantly. 

 Both brake and clutch are operated by direct current supplied 

 by a small motor-generator set. 



A 24 .X 66-inch Birmingham calender is driven by a Westing- 

 house 75-horse-power, 230-volt, direct-current motor supplied 

 with current at both 120 and 240 volts from the generator shown 

 in Figure 2. It is evident that it would be less expensive to 

 drive the calender with an alternating-current motor which could 

 take its current directly from the line and thus eliminate the 

 generator; but a direct-current motor is preferable, because there 

 ij no practicable method of getting satisfactory speed variation 

 with an alternating-current motor, whereas with a direct-current 

 motor any desired speed range can be obtained. In the present 

 instance the highest speed of the calender is four times its lowest 

 speed and there are 22 steps between, so that every calendering 

 operation can be carried on at the most suitable speed. 



Another interesting point is the use of current at two voltages 

 for this motor. It is easily possible to build a motor that will 

 provide a 4 to 1 speed range on one voltage, but such a motor 

 would cost considerably more than the present one, which pro- 

 vides only a 2 to 1 speed range on each voltage ; and since the 

 use of two voltages adds but little to the cost of the generator 

 and the controller, a less expensive outfit is provided. 



The calender controller, which is of the Westinghouse auto- 

 matic type, consists of two principal parts : a drum controller 

 and a panel on which are mounted various automatic switches ; 

 while on the calender itself are placed "start" and "stop" but- 

 tons. When the operator desires to start the calender he moves 

 the drum controller handle to the notch which he knows from 

 experience will correspond to the speed he desires ; he then 

 presses the "start" button. The motor now starts and comes 

 up to speed, the magnetic switches on the panel automatically 

 making the proper connections. Should a change of speed be 

 desired, the controller handle is moved in either direction, 

 causing the motor to change its speed to correspond. Pressing 

 the "stop" button not only cuts off the current but causes 

 dynamic braking connections to be made by the automatic 

 switches, which brings the calender to an abrupt stop. Safety 

 switches, operated by means of ropes hanging down on each 

 side of the calender, stop the calender in the same way. 



The Royle tubing machines, which form inner tubes, are driven 

 by 20-horse-power, 220-volt, 685-r.p.m., Westinghouse squirrel- 

 cage motors. The drying rolls, the grinding and buffing wheels, 

 and the machine tools in the machine shop are also motor driven. 



NEW POLICY OF BUYING RUBBER-COVEHED WIRE. 



Manufacturers and jobbers are making a better profit in rubber- 

 covered wire today than ever before. The demand is large and 

 the output is not sufficient. Rubber-covered wire, being a staple, 

 never was very profitable for the jobber. Until quite recently 

 it was sold on a basis of the best price. Thus a buyer would 

 place an order at today's prices, say 21 cents, for four months* 

 delivery. If at the delivery date the prevailing price was 18 cents 

 the buyer expected this price and received it, although the con- 

 tract was made at 21 cents. If, on the other hand, the price had 

 advanced to 23 cents the buyer held to the contract price of 21 

 cents. The buyer therefore was protected against any advance 

 in the market but he also received the benefit of any decrease in 

 market prices. 



Under such a scheme it was nothing more than heads the 

 buyer wins, tails the seller loses. With the margin of profit 

 always small it often reached the vanishing point on a rising 

 market. Today, however, all of this has been changed. Wire is 

 bought at the delivery market price of copper-wire base. The 

 jobber buys this way from the manufacturer and the contractor 

 from the jobber. The benefits of a rising market are now going 

 to the seller. [Electrical World.] 



FOREIGN IMPORT DUTIES ON RUBBER SPONGES. 



THE accompanying statement of foreign import duties on 

 rubber sponges imported into the various countries given, 

 has been corrected to December 1. 



When two or more rates of duty are shown for the same 

 article, products of the United States, as a rule, are admitted 

 at the lowest rate ("conventional" or "minimum"), except: (1) 

 Into France and French colonies, where, in the case of most 

 articles, the "general" rate is applied; (2) Into Canada, where 

 the "general" rate is applied; (3) Into other British colonies, 

 where the "preferential" rates, if any, are withheld from all non- 

 British imports. 



While every care has been taken to insure accuracy, the rates 

 are not guaranteed and it is advisable to make small trial ship- 

 ments to test them. As changes in the duties are likely to occur 

 at any time, frequent verifications arc advised. The surtaxes 

 noted in the South .American table have not been added to the 

 rate. 



FOREIGN IMPORT DUTIES ON RUBBER SPONGES. 



Rate per 100 Kilos. 

 (220 Pounds.) 



Europe: 



Austria-Hungary 



Belgium 



Bulgaria 



r)enroark 



Finland 



France 



Germany 



*Greece 



Italy 



Netherlands . . . . 

 Norway 



Con- Rate per cent 



Weight General. vention. ad valorem. 



Net $20.00 $16.00 



Net 10 



Net 58.00 



Net 18.75 



Net 11.34 



Net 72.37 48.25 



Net 9.52 9.52 



Net 77.20 



Net 9.65 9.65 



Net 5 



Net 34.84 26.80 



9.65 



29.00 

 77.00 



4.82 

 52.80 



Portugal Net 45.60 



Roumania 9.65 



tRussia Net .113 



Serbia Net 86.85 



Spain Net 115.00 



Sweden Net 32.16 



Switzerland Gross 7.72 



Turkey 



United Kingdom Free 



Rate per Kilo. 

 South America: \'aIuation. [2.2 Pounds.] 



Bolivia Gross $1.55 25 



(Surtax, 2 per cent of official valuation.) 



Colombia Gross $1.00 . . 



(Surtax, 2 per cent of duty.) 



Ecuador Net .145 



(Surtax, 125.5 per cent of duly.) 



Paraguay 4.82 42 



(Surtax, 1.5 per cent ad valorem, based on official valuation.) 



Peru .729 



(Callao, Salaverry, Paiia and Pisco, surtax, 10 per cent of duty. Other 

 ports surtax 8 per cent of duty.) 



Uruguay 31 



Venezuela Gross .482 .. 



(Surtax, 56.55 per cent of duty.) 



• Rate per 100 Okes [2.822 pounds!, 

 t Rate per Funt [14^ ounces]. 



Compiled by the Bureau of Foreign and Domestic Commerce, 

 Washington, D. C. 



AMERICAS FIRST NAVAL DIRIGIBLE. 



The United States Navy's first dirigible balloon, the DN-1, 

 has been shipped to the Naval Aeronautical Station, Pensacola, 

 Florida, for final flying tests, the preliminary power plant and 

 blower tests having been previously passed by the government 

 inspector at the factory of the constructors, the Connecticut Air- 

 craft Co., New Haven, Connecticut. 



The DN-1 is of the non-rigid type, the gas bag maintaining 

 its shape by the pressure of the contained gas, and the gondola 

 being suspended by numerous ropes and cables fastened to the 

 "belly-bands" of the bag. 



The envelope of the bag is of double-ply rubberized cotton 

 fabric; strength, 70 pounds per inch for both warp and weft; 

 permeability, 35 cubic feet per 24 hours at two feet water 

 pressure. All seams are extra wide, with double rows of 

 stitching. The ballonets are made of double texture fabric; 

 strength, 40 pounds for warp and weft. 



All of the fabric, for both main envelope and ballonets, was 

 furnished by the Cambridge factory of the United States Rubber 

 Co., the shaping of the big bags and the setting-up of the balloon 

 being done in the Naugatuck factory. 



