ON THE SCREW GAUGE. do7 
Mr. Foster informed the Committee that in the experience of his firm 
these limits are found to be convenient for all screws connecting ordinary 
pieces of mechanism. 
Tests of B.A. Screws by Hervé Diameters. By W. A. Price. 
Of the measurements given in the following table all, excepting the 
No. 8 steel and No. 11 brass screws, were made with a gauge of which 
the zero was out of adjustment, the measures to be reduced by 0002 in 
the first 9 columns. 
These measurements. were made to ascertain within what limits a 
screw maker can work, not as chausson screws with their theoretical 
diameters. 
It seems that 1-2 inch below the full diameter is all that is required 
for brass screws Nos. 0 to 11, and that the same is required for all sizes. 
It is clear that steel screws are more troublesome than brass, but the 
lot of No. 4 steel examined were probably not made with sufficient care. 
The margins are : 
1:2 1:0 =) 11 ‘9 1:8 8 1:2 1:0 1:2 a) 
(16) (3:2) (3:0) (@3219) (1:5) 
The figures in brackets in each case include the screws, even those that 
are clearly too small to pass. 
‘| No. 0 No. 0 No. 2 No, 2 No. 4 No. 4 No.6 | No.6 | No.8 | No.8 | No. 11 
Brass | Brass Brass Steel Brass Steel Brass | Steel Brass | Steel Brass 
2373 *2385 *1852 1852 1424 1438 1110 ‘1111 0865 “0860 “0595 
“2372 2382 *185C “1851 "1424 1437 1109 1110 “0864 “0858 “0594 
"2371 2382 "1850 "1851 1423 1434 1108 “1110 “0863 “0857 “0594 
+2370 “2380 1849 “1851 1422 1434 “1106 ‘1110 *O86L “0857 “0594 
*2370 *2380 "1849 “1850 1421 1433 “1106 “LLLO “0860 “0857 0593 
2370 “2380 "1849 “1850 1421 1432 1106 1110 “0860 “0857 "0593 
*2370 "2380 1849 1850 "1421 1431 “1105 1109 “0860 “0855 0593 
*2370 2379 1849 1849 1421 1431 1105 1109 0860 “0855 “0593 
“2369 2379 +1848 1848 “1420 1430 “1104 1109 “0859 “0855 “0593 
2368 2379 1848 1848 "1420 1430 “1103 1109 “0859 “0854 “0593 
"2368 *2378 *1848 1848 "1420 "1430 “1103 ‘1109 “0859 0854 “0592 
2367 2378 1848 1847 "1420 1429 +1103 1109 0859 “0854 0592 
2367 2378 1848 “1845 1419 "1428 1103 1109 0859 “0853 “0592 
2365 “2378 1848 1844 "1419 “1428 1103 “1109 “0859 “0852 0592 
"2364 2377 1848 “1843 1419 "1426 1103 ‘1108 “0858 “0852 “0591 
"2364 *2377 "1847 “1842 1418 *1425 “1103 “1108 “0857 “0852 “0591 
2363 2376 1847 1842 1418 1422 1103 1105 0856 “0852 “0590 
*2362 “2375 1842 1842 "1418 "1422 “1103 “1102 "0856 *O851 “0590 
* 2362 "2309 .1842 1841 1417 1419 1102 1102 “0856 “0850 0589 
* 2362 _— 1845 “1841 “1417 1421 1102 “1101 "0855 “0850 “0589 
* 2361 _— "1845 1841 1417 "1420 _— “1101 — “0850 *0587 
“1845 (it 832 “1416 "1412 Mean “1100 Mean “0849 “0586 
Mean} Mean 1843 *1830 1416 1412 _ — —_ = -- 
2368 +2379 1843 | “1825 1415 “1410 1104 "1099 “0859 0849 | (0581 
1820 1410 —_— 1094 _ “0848 | (| :0580 
Omitting 1409 — { “1090 _ "0848 — 
Mean | last four| Mean 1408 Omit- Omit- 
18475 Mean "14205 1408 ting M ting 
1846 1408 last 2 “0833. | last 2 
Mean Mean zs Mean 
Omitting “1108 “0592 
last 8 
1429 
The No. 11 brass screws were a lot that Hervé had been asked to make 
with especial care. 
