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April, 1919 in, the conducting strip is magnified several hundred times on the scale by “means of a combination of wires and a deflecting spring. The conducting strip is made of noncorrosive material. The _ separat- ing posts have the same temperature coefficient of expansion as the con- ducting strip, so that changes in the surrounding temperature do not cause an error in the reading of the instru- ment. The instruments are furnished in two forms, for flush mounting and portable. The instrument shown is of the portable type. The flush mounting form is of the round open- face type. The face is 3 inches in diameter, and the diameter outside the flange is 334 inches. It has a black case and rim, with white dial. The portable form illustrated is mounted in a morocco-leather-covered wooden case with heavy glass over the dial. The case is 334 x 43% inches and 2 inches thick, The scale plate is made of metal, and the scale sub- tends an arc of 90 degrees, being 23% inches long. The flush mounted meters have a guaranteed accuracy of 2 per cent while the portable meters, with hand marked scale, can be expected to show an accuracy within I per cent of full. scale. Standard meters are for 1, 2,.and..5 amperes. . It is pointed out that care must be exercised not to subject the instruments to more than 200 per cent load. Portable Electric Drill For Esommodabae : Haper shank drills up to %-ineh*’ diameter,... the Black & Decker Mig. Co.,. Baltimore, recently developed the tool shown in the accompanying illustration. This drill weighs 27 pounds and is driven by a %-horsépower motor. The drill -is 17 inches tong and “534 ‘inches in diameter and- haggan. offset spindle to accommodate ffi drill which is’ do- cated 234 inches? arom thé’ center of “the motor. spindle: LE ae Tob - This ‘tool hasan. cgi ue con ‘trolling © dévice. . This ” all. ‘has: a ELECTRIC DRILL FOR SHIPYARD USE “years. THE MARINE REVIEW 213 MULTIPLE SPINDLE, HARTER oes capacity up to %- inch? “hole, and is designed to handle a variety of work in the shipyard or machine: shop where current is available. plates corte wank a to make. sure that fe tae furnish a correct seating for the rivets is a. problem that has confronted ship- builders and- boilermakers for many With the object of. providing a rapidiand accurate means for prose- “euting ‘this. work, thé Hilldrill Co., Philadelphia, recently designed the machine shown inthe accompanying illustration. Be ies 2 This machine 1s*designed to accom- modate flat plates as:well as those that have been previously rolied: to a con- tour, boiler plates for-an- illustration. The construction.,of the,,machine is made as simple as possible and it said that it can. be operated without highly skilled labor. These machines are built in various lengths the longest being 40 feet. This length of machine will drill 100 rivet holes at, one, operation, at one setting of the work. The machine consists of two end housings which are securely anchored to a.concrete foundation. The housings are tied together by means of two heavy flanged pipe units. The object of..using this design is to secure ample strength with a minimum amount of weight. At the front of the machine, the housings are fastened together by means of a_ substantial I-beam member. On each housing is a slide which n steel’ FOR SHIP. AND’ BOILER PLATE WORK carries the table on which the work is located. The table is raised and lowered through the medium of four 3-inch elevating screws: which are actuated by means of .a worm drive. The crossrail On: “which are mounted the drill* heads is made of I-beam section. “Tt is finished from end to '“end. between-the flanges to form a bearing surface for the four endles chains that drive the drill spindles. This unit is also accurately finished to accommodate the drill spindle heads. The chains that rotate the drills are driven by sprockets at the ends of the crossrail. At the righthand end, the sprockets are keyed to the ‘shaft that forms the driving member “while the sprockets at the other end of the machine are idlers. The drills are fed downward by a mechanism operated by’ two © large spur gears which operate simultaneous- ly. This mechanism feeds the cross- rail and drills down witn'a slow mo- tion: while the return’*movement is almost instantaneous. When the cross- rail reaches its highest position a clutch..is thrown — out. automatically which stops the machine. The machine embodies several in- teresting features. The drills are fed down . automatically and when the work is clamped in place a pressure of 20 tons is exerted which tends to straighten out any irregularities in the material to be drilled. It is said that the machine is particularly . adapted for boiler plate work. In drilling the drums of boilers, the inner butt strap is placed in position, as shown in the accompanying illustration, where it 1s 4 % . i: 4 a a ‘ g b, ; ERIN Ein Fee ALLE vy algae NED TOR Ie