210 



CENTRAL SCIENTIFIC CO., CHICAGO, U. 8. A. 



Model 155. 



4524. 



4526. 



4532. 

 4534. 



4546. 

 4548. 

 4550. 



4572. 



4574. 



Model 156. 



METERS, IMPERIAL ALTERNATING CURRENT. 



METERS, SWITCHBOARD. Standard electromagnet construction, hand calibrated scales, which, 

 as iu all A. C. Meters, cannot be used with great accuracy over the first 20 or 25 per cent of 

 their range. Best quality jewel and pivot bearings; brass case, finished in baked enamel and 

 dust proof. Diameter, 4 inches. 

 AMMETEBS. 



No 



Eange, amperes 



Smallest division, amperes 



Each 



VOLTMETERS. 



A 



1 



0.02 

 $9.50 



B 



3 



0.05 

 9.50 



C 

 5 



0.1 

 9.50 



D 

 10 

 0.2 

 10.35 



E 

 15 



0.25 

 10.35 



F 



30 



0.5 



10.65 



No 



Range, volts 



Smallest division, volts. 

 Each . 



A 



10 



0.2 



9.50 



B 



15 

 0.25 

 9.80 



C 

 30 

 0.5 

 9.80 



D 



50 



1 



10.35 



E 



150 



2.5 



11.50 



F 



250 



5 



12.65 



METERS, WESTON ALTERNATING CURRENT. 



METERS, PORTABLE, Model 155. These instruments are perfectly dead beat, extremely sensi- 

 tive and quickly and accurately respond to the most minute as well as to the greatest fluctua- 

 tions in current strength, or in potential difference. They may be used on circuits of any 

 frequency, within the limits of engineering practice of today, without sensible error in their 

 indications. Provided with hardened steel pivots, jeweled bearings and mounted in neatly 

 finished dust-proof wood cases. Dimensions 7x714x3% inches. 



AMMETER, 0-10 amperes $21.25 4538. VOLTMETER, 0-75 volts 23.15 



AMMETER, 0-25 amperes 21.25 4540. VOLTMETER, 0-125 volts 23.15 



METERS, SWITCHBOARD, Model 156. These instruments are of a high standard of excellence, 

 indicate the same whether left in circuit for a minute or permanently, may be used on circuits 

 of any ordinary frequency, are entirely dead beat, and are provided with a remarkably uniform 

 scale. Diameter of case, 7.25 inches; depth of case, 3.15 inches. 



AMMETER, 0-10 amperes 16.90 



AMMETER, 0-25 amperes 16.90 4554. VOLTMETER, 0-75 volts 18.15 



AMMETER, 0-50 amperes 17.20 4556. VOLTMETER, 0-130 volts 18.15 



BOTH ALTERNATING AND DIRECT CURRENT. 



AMMETERS, PORTABLE, Model 370. Instruments are of the electro-dynamometer type, which 

 may be used either on direct current circuits or on alternating current circuits of any frequency 

 up to 133 cycles per second. Contained in polished mahogany boxes, 8x10*4x5% in., with carry- 

 ing handles, locks and covers. (See illustration on page 211.) The scales are 5% in. long and 

 are of necessity not uniform so that they cannot be used with great accuracy over the first 20 or 

 25% of their range, e. g., the 10 ampere scale is graduated in tenths from 2 to 10 amperes and 

 this range covers 5 in. of the length of the scale. Parallax is prevented by use of mirror scale 

 plates and knife edge pointers; the entire coil system is mounted in a double closed iron shield; 

 the pointer responds very quickly to changes in the applied current; the instruments are not 

 affected by ordinary changes in external temperature and are free from working errors; and an 

 accuracy of 14 of 1 per cent, of the full scale value is guaranteed on the working part of the 

 scale. For both Alternating and Direct Current. 

 MILLIAMMETERS, single range. 



No A B C D 



Range, mil-amperes 50 100 500 750 



Approx. resistance, ohms 167 26.5 1.2 0.9 



Each $84.40 84.40 84.40 84.40 



AMMETERS, double range. 



No 



Ranges, amperes 



Each 



A 

 2-1 



93.75 



B 



5-2.5 

 93.75 



C 



10-5 

 93.75 



