TRANSACTIONS OF THE SECTIONS. 205 
the average yield at Farnley. The fracture of this stone showed a blackish grey tint, 
and yielded by analysis— 
Metallic iron ........+ese0++444 39°4 per cent. 
Silica and alumina........... .+» 14°9 per cent. 
Sulphur ........ afeleisisis «ss aie etal mmOnCEECOIGs 
Oxygen, carbonic acid, &c. ...... 44°9 per cent. 
A singular affinity seems to exist between the ore and the better bed coal in this 
district. The results obtained from other descriptions of stone have not been satis- 
factory. With respect to the fuel employed, the better bed coal burnt free from 
sulphur, and, as this was one of the chief obstacles in the manufacture of iron in this 
country, such a coal was a great desideratum. Mr. Wood, of Leeds, had lately 
analysed one sample of this coal, and the following were the results :— 
Carbon ....... Speteabiaheieasicia’ et olein «sufi. 100 
EVVOrOgen\6esinies cee sissiswiiess ss . 2000 
SSCL T aaa ola folaiyieitorats Shsvavshavalebe sory *196 (very small), 
UNG liftetelats at aisieie/sia)eistal sist tivist sia sin eA OU 
Oxygen and nitrogen............ 15°404 
100°000 
Other analyses would have to be made on different samples of the coal before the 
average amount of sulphur could be determined with precision, but this first essay 
was satisfactory, inasmuch as it placed the better bed coal of this district in the 
foremost rank amongst the pure coals of England; and it was to the excellence of 
this fuel, as observed in the memoir of the Geological Survey already referred to, 
that the good quality of the iron manufactured at Low Moor, Bowling, and Farnley, 
was mainly attributable. In conclusion, he referred to the points of importance in 
connexion with the process of refining the pig metal at the Farnley Iron Works, 
which were peculiar to that establishment. The first had reference to the introduc- 
tion of steam into the refinery along with the blast; the second was the introduc- 
tion of steel into the refineries in conjunction with the pig metal. The refined metal 
thus produced presented a pure silvery fracture, and a perfectly homogeneous texture. 
On Steam Tugs employed on the Aire and Calder Navigation. 
By W. H. Bartruotomew, MLC. 
The navigation to which the subject matter of this paper refers is a combination of 
natural and artificial : throughout it has a navigable depth of 7 feet. The canals, or 
artificial portion, have bottom and surface widths respectively of 25 to 30 feet, and 60 
to 66 feet; the sectional area of water-way varying from 350 to 380 superficial feet. 
The locks, which occur at varying distances of from 9 to 2 miles, admit vessels of 
dimensions not exceeding 64 feet long and 18 feet beam. 
An improved system of haulage was introduced in 1853 by the construction of a 
steam tug (which had been followed by several others), designed with the combined 
object of providing motive power for a train of boats and capability for carriage of 
cargo. These tugs were in length 63 feet 6 inches, having beam respectively of 11 feet 
and 12 feet 6 inches, depth of hold 7 feet 3 inches, immersed midship sections 64 and 
72 square feet respectively, displacement with such immersion 40 tons for cargo, and 8 
to 10 tons for machinery and stores. The engines and boilers were fixed in the after 
portion of the boats, and occupied 20 feet of their length; and 30 feet were devoted 
to cargo and 12 feet 6 inches to accommodation for the crew. The remainder of the 
length was taken up by bulkheads, stores, &c. The peculiar machinery of these boats 
was next illustrated by a technical description and plans; and the author then pro- 
ceeded to show that by a new arrangement of the screw, adopted in other more recent 
tugs, there was a considerably lower per-centage of “slip.” This screw consisted of 
two ordinary screws fixed on the same shaft at right angles, or otherwise, to each 
other, having an intervening space of six or more inches between them, and conse- 
quently their planes of rotation were different; their pitches also varied, the after 
screw having the greater. This application had proved to be most successful. In 
working these tugs the pressure of steam was regulated to the duty to be performed, 
and had varied from 100 Ibs. to 220 lbs., but did not often exceed 160 lbs. per square 
inch, The general speed of the engines was 180 revolutions, or 360 feet speed of 
