262 Mendenhall and Waidner — Galvanometers, etc. 



Galvanometer and Con- 

 stants when tested. 



Wadsworth (Phil. 

 Mag., xxxviii, p. 

 553). 



4 coils, 50mm. 

 ext. diam., 2mm. int. 

 and 40mm. deep. 

 Each coil wound in 

 5 sections, with 

 2396 turns. 

 i?=86 ohms (series) 



Nichols E. L.and 

 E. E. (Phys. Rev., 

 i, p. 2). 

 B=9B ohms 



(parallel) 



Suspension System. 



10 small magnets 

 in each group (5 on 

 each side of staff, 

 varying from 2- 

 3mm. in length) 

 made from smallest 

 size sewing needles 

 (untreated). 



Glass 150mm. 

 long, weighs omg. 



Mirror (concave) 

 2 - 5mm. diam. and 

 weighs 12mg. 



Sensibility and condi- 

 tions of use when 

 tested. 



C=4 x 10~ n amp. 

 per mm. 

 Scale dist.= 100cm. 

 T (complete) = 



20 sees. 

 R=:86 ohms. 



Paschen Wied. 

 Ann., xlviii,p. 284). 



4 coils, 40mm. 

 external and 5mm. 

 internal diam. 

 "Wound with graded 

 wire, about 1200 

 turns in each coil. 

 i?=60 ohms. 



"Wt. of systems 

 48mg. 



Each group has 

 13 magnets 1 to 

 1*5 mm. long, on 

 both sides of glass 

 staff 3mm. apart; 



Mirror 2mm. dia. 

 03mm. thick. 



5cm. quartz fibre. 



Wt. of system = 

 5mg. 



Mendenhall and 3 magnets in each 

 Waidner. group. 



4 coils, ext. diam. Total wt. lmg. 

 = 15mm., internal) Wt. of magnetic 

 diam. = 2 mm. 6 part of needle = 

 sizes of wire, 500|*68mg'., length of 



0=1-3 x 10- 10 a?^. 

 per mm. 



Scale dist = 150cm. 

 T (complete) = 



10 sees. 

 R=9 3 ohms. 



(7=3-3 x 10- 12 amp. 

 per mm. 



Scale dist. = 300cm. 



T = 15 sees, (ape- 

 riodic, i. e , has 

 only one turning 

 point). 

 R = 60 ohms. 



turns on each coil. 

 JR=S ohms 



(in parallel) 



magnets =ri5mm. 

 Plane mirror, 

 •9mm. x 1mm. 



C=5-6 x 10- n amp. 

 per mm. deflection. 

 Scale dist.=200cm. 

 T=9 sec. complete 

 aperiodic (i. e. has 

 only one turning 

 point). 



Zero stable. 

 R=3 ohms. 



Deflections per micro- 

 ampere when scale 

 dist.=iooo scale divs. 

 complete period = 

 io sees. Resistance 

 =1 ohm. 



675 



2200 



5800 



6090 



Thompson Physical Laboratory, 



Williams College. 



