76 Mr. R. H. M. Bosanquet on the Magnetic 
experiments thus made. They also show the degree of 
accuracy attained by the Fourier’s series, by which I have 
endeavoured to represent as a function of G. 
EH. Forged Ring Crown Iron. 
Mean diameter. . d@ =10:0385 centim. 
Bar-thickness: pa. 2 12935 
Number of coils . n = ARG 
p cale.=144 + 221 cos 0 
+ 2000{sin 6+ sin 20+ 5) sin 30 +45 sin 46}, 
where 
g— 8 degrees 
100 °° 
=a 
b be 
35 | Dyers, 3. |————_ Ditts 
Obs. | Cale. Obs. | Cale. 
129°7 | 437 | 4387 0 11516 | 1615 | 1625 | + 10 
2391 | 493); 498 | + 5 | 13276 | 13881 | 1207 | —174 
21743 | 1474 | 1470 | — 4 14017 | 1047 | 1017 | — 30 
31869 | 1817 | 1836 | +19 | 15000 635 | 732 | + 97 
5181°7 | 2163 | 2199 | +36 | 16380 218 | 349 |) +131 
6403°4 | 2234 | 2229 | — 5 || 17245 11%.) 19 eae 
FE. Forged Ring Crown Iron. 
Mean diameter . . d =22:1 centim. 
Bar-thickness 6° 2R= 1:292 |. 
Number of coils. . » +=1118. 
pcale, = 200+ 1630{sin 6+4 sin 20+4 sin 80+ 4,sin 46}, 
where 
_ 8 
é= 700 degrees. 
pe 
3. —_—____—_—__| Ditfs. 45. Diffs. 
15108 | 208 | 208 0 6438°4 | 1825 | 1847 | + 22 
142°55 360 | 284 | —76 7655°3 | 1704 | 1749 | + 45 
512/97 587 | 502 | —85 10767 1581 | 1481 | —100 
2783'8 1592 | 1572 | —20 12537 1252 | 1258; + 6 
3616°5 1784 | 1784 i) 13900 1000 |} 989; — 11 
4282°6 1869 | 1858 | —11 15025 692 | 749 | + 57 
57466 1895 | 1890 | — 5 18834 150 60 | — 90 
