355
OF ENGINEERING FOBMULÆ.
Telegraph Construction, by Paget Higgs, LL.D..
C.É.
Table for calculating Inner and Cuter Diameter of
Iron Sheathing.
Rule: Multiply diameter of wire by constant
corresponding to number of wires. The diameter
of wire may be in mils, inches, or millimetre«.
To use this table for outer diameter of strand, take
the number of wires around the central for entry.
The inner diameter is obtained from the outer
diameter by subtracting 2,
No. of Wire». Outside Diameter. Log. ?fo. øf Wires. Outside Diameter. tog.
3 2-155 0'33345 17 6-442
4 2*414 0-38274 18 6-T59 0'82988
& 2-701 0-43152 19 1-075 8-84973
6 3-000 0-47712 20 7-392
7 3'305 0'51917 21 7'709 0'88672
8 3'613 0'55787 22 8-027 0'90455
9 3’924 0’59373 23 8-344 0-9213?
10 4’236 6-6269Ö 24 0-93757
11 4-549 0'05792 25 8-970 8'05323
12 4-864 0-68699 . 26 »•2»& e-9(>830
13 5’179 0'71425 27 9-614 0-98290
14 6-494 0-73989 28 9’931 0-99699
15 5-810 0'76118 29 10'24» 1-01072
16 6-126 0-78718 30 10-567 1-02401
2 a2