284 Mr. W. H. Preece. [Dec. 22 ; 



Platinum. 



Diameter of wire. 



Current in amperes. 



Jb using 

 current 

 calculated 

 from the 

 formula 

 ad 3 ' 2 . 



Amperes. 



Constant 



" a " 

 when d 

 expressed 

 in inches. 



In 



inches. 



In 



centi- 

 metres. 



Standard 

 wire 

 gauge 

 No. 



Shellac 



Hake 

 melted. 



Wire 

 red hot. 

 Visible 



in air. 



Wire 

 fused . 



o-oio 



0'025 



33 



2-365 



3-915 



6-281 



6-008 



6278 -8 



0-012 



0-030 



30 



3 -060 



5-424 



8-076 



7-90 



6141 -3 



0-014 



0-036 



28 



3-916 



6-688 



9-625 



9 95 



5808 -4 



-018 



0-046 



26 



4-936 



8-320 



13-378 



14-50 



5537-1 



0-020 



0-051 



25 



5-926 



11-430 



17 -780 



17-00 



6282 3 



-026 



0-066 



22 



8-808 



16-316 



25 -778 



25 -20 



6145 8 



030 



-076 



21 



9-618 



20-32 



30 -47 



31-20 



5863-6 















Mean = 



6008 -2 



Note. — The ratio of perceptible warmth : red heat : fusing point is (roughly) as 

 1 : 2 : 3 in platinum. 



German Silver. 



Diameter^ of wire. 



Current in amperes. 



Fusing 

 current 

 calculated 

 from the 

 formula 

 ad*' 2 . 



Amperes. 



Constant 

 "a" 



when d 

 expressed 

 in inches. 



In 



inches. 



In 



centi- 

 metres. 



Standard 

 wire 

 gauge 

 No. 



Shellac 



flake 

 melted. 



Wire 

 red hot. 

 Visible 



in air. 



Wire 

 fused. 



005 



013 



39 



0-910 



1-530 



2 -150 



2-062 



6078-4 



0-007 



0-018 



37 



1-406 



2-150 



2-812 



3-415 



4799 -3 



0-009 



0-023 



34 



1-905 



3-492 



5-000 



4-978 



5860 -7 



0-012 



0-030 



30 



2-977 



5-460 



7 -693 



7-666 



5849-8 



0-014 



-036 



28 



3-639 



6-619 



9-926 



9-660 



5989 -3 



0-018 



0-046 



26 



4-757 



8-894 



13-235 



13 560 



5478-1 



0-020 



-051 



25 



5-790 



11-167 



15 -717 



15-880 



5550-5 



-026 



0-066 



22 



9-846 



15 342 



23 - 740 



23 550 



5060 -0 



0-030 



0-076 



21 



15-055 



23 -740 



30 -690 



30-300 



5901-1 















Mean = 



5618 6 



