1S46.] 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



343 



the mercury. Analysing the two powders, sulphur was detected. But as 

 a yellow compound of mercury and sulphur contains oxygen, and as no 

 oxygen was found in the black powder, it may be questioned wliether the 

 first compound takes oxygen from the air of the bulb and returns it in pas- 

 sing to the state of the black one, or that some hitherto unknown exchange 

 takes place between the elements of the glass and the mercury. 



" On the Corrosion of Iron Rails in and out of use." liy R. Mallett. — 

 The researches on this- subject are still in progress, experiments are being 

 made upon six ditTerent lines of railway. The principal facts already ascer- 

 taiued are : — 1st. That there is a real difference in the rate of corrosion be- 

 tween tlie rails in use and out of use : — that this appears to be connected 

 with their peculiar molecular condition so induced. 2nd. The determination 

 of the complex conditions as to magnetism, which affect rails some time in 

 use, producing both induced and permanent magnetism in the rails, each rail 

 being magnetic with polarity, and having from four to eight separate poles 

 each. 



Mr. Hunt stated his confirmation of the experiments of Ritter — that mag- 

 netism had the power of protecting iron from corrosion ; — to which he re- 

 ferred the protecting influence exerted on the rails in use on railways. 



" Notice of a Gas Furnace for Organic Analysis." By Dr. Percy. — This 

 was an ingenious arrangement, by which gas, burnt, mixed with air, through 

 wire gauze, was substituted for charcoal. Its advantages are its extreme 

 cleanliness, and the power which the operator possesses of regulating, at 

 will, the heat, — which is not practicable iu the ordinary furnace for organic 

 analysis with charcoal. 



Section C. — Geology. 



" On the Northwich Salt-Field," by G. W. Ormerod.— The rock-salt 

 of Northwich is part of the New Red Sandstone series : it forms two 

 strata, the uppermost of wh-ch is 75 feet thick, and the lower 105 feet; 

 they are separated by 30 feet of stone, containing veins of salt. Through- 

 out the district, the brine is reached at the same level, about 87 feet below 

 the river Weaver; and varies uniformly in all the shafts when any change 

 takes place. In this district there are three faults, which have displaced 

 the strata to a considerable amount. The first fault is a throw-down to the 

 east of 400 yards; it intersects the South Lancashire coal-field, and passes 

 into Cheshire, along the valley to the west of Bellefield and Hill Clifl', a 

 range of New Red Sandstone (hunter sandstein), capped by the ripple- 

 marked beds denominated " water-stones," iu which the foot-marks of the 

 Cheirotherium occur ; the summit is 352 feet above the level of the sea. 

 Near Northwich this fault appears to pass into another, which is an wp- 

 i/iroK! to the east of 460 feet, and passes also through the South Lanca- 

 shire coal field, by Wigan Chord, and east of Warrington into Cheshire, 

 when it continues along the valley east of the Bellefield range. Through 

 the coal district this line is proved by nismerous workings; and in the salt 

 district, by the extent to which the workings and the sinking of the land 

 have gone. The third great fault, passing by Northwich, ranges by south- 

 west to north-east, passing near Holt, and running up the valley between 

 the Peckforton Hills and the low range occupying the east side of the Dee. 

 This valley is occupied by marl, in which saline springs are frequent. At 

 Northwich the line runs in a north-easterly direction, forming the north- 

 west boundary of the rock-salt. The subsidences already mentioned as 

 taking place in the salt district are either sudden or gradual, and have been 

 noticed for many years. At the yard of the Weaver Navigation Office the 

 sinking is at least six feet; and on the road from that place to Winningtou 

 the depressions are shown by cracks in houses and visible subsidences iu 

 the land. From the same cause, a lock and a factory have required to be 

 removed, meadows are laid under water, and the towing-path by the river 

 has had to be raised. The Whittou Brook has also been made six feet 

 deeper, to enable the navigation to proceed as formerly. 



Mr. Phillips observed, that one of these faults laid down in Mr. Orm- 

 erod's map was 50 miles long, and one was in the direction of the magnetic 

 meridian. In the south of England, the New Red Sandstone became 

 much thinner, less complicated, and was deficient in salt. 



Sir H. Die La Beche stated that the variegated tints of the water-stones 

 were due to a diderence in the amount of oxydation of the ores they con- 

 tained. The decomposition of vegetable matter had, in some places, re- 

 duced the per-oxide to the condition, comparatively, of a prot-oxide, — 

 changing the red colour of the rock to a pale blue. 



Mr. Greesoogh remarked, that salt existed below the coal-measures in 

 Durham, as well as in the New Red Sandstone, whilst the salt beds at the 

 base of the Carpathians were of tertiary age. 



■' On certain Deviations of the Plumb-line from its Mean Direction, as 

 observed in the neighbourhood of Shanklin Down, in the Isle of Wight, 

 during the progress of the Ordnance Survey," by Mr. W. Hopkins. — The 

 difference of latitude between Greenwich and the station of the Ordnance 

 surveyors at Dunnuse, on the north side of Shanklin Down, as determined 

 by triangulation, was greater by 2'22 seconds, than as determined by 

 zenith sector observations. When, however, a new station was chosen on 

 the south side of Shanklin Down, the difTerence of latitude, as determiutd 

 by triangulation, was less by 3'99 seconds than it appeared to be when 

 determined by the zenith sector. These discrepancies would be accounted 

 for, if the mass intervening between the stations at Shanklin Down were 

 sufficient to produce, by its attraction on the plumb-line, the observed de- 

 viations. The requisite calculations for proving the adequacy of this 

 cause had not been made; the tendency, however, would necessarily be to 



produce effects of the same nature as those observed ; and the author 

 thought it probable that the intensity of the attraction of the hill would be 

 found sufficient to account for the phenomena. 



Coal of India. 



Mr. Ansted read an analysis of a report to the Indian Government on the 

 coal of India. — The subject of coal iu reference to our Indian territories has 

 for a long time been looked upon as of great practical importance ; and the 

 increase of steam navigation, as well as the proposed introduction of rail- 

 roads into that country, renders every matter connected with the subject in 

 the highest degree interesting. I have received, since my arrival at South- 

 ampton, through the kindness of Colonel Sykes, a copy of a report recently 

 made to the Indian Government, giving an aperfu of the information at 

 present obtained concerning the various beds of coal chiefly in Northern 

 India, and I cannot help thinking that an account of the information thus 

 communicated may be generally useful, especially as much of it is new, 

 and a very large proportion of the remainder, although known to those 

 who have been long accumulating matter that bore reference to this sub- 

 ject, is little familiar to the great body even of those most interested ia 

 Indian aflairs. 



The coal-districts of India, as determined in this report, may be consi- 

 dered as five in number, — three of these are in Northern India, and one in 

 Cutch, while the fifth includes the province of Arracan and the coast of 

 the Burman empire near Tennasserim. Of these the Cutch coal is cer- 

 tainly not of the carboniferous epoch, and it appears to be of little import- 

 ance at present, and unpromising. It has also been described by Captain 

 Grant, in the Transactions of the Geological Society, and therefore I will 

 not now allude to it. I shall endeavour to describe, first, the chief points 

 of importance with reference to the great and continued series of the North 

 Indian coal-fields, and then allude shortly to the prospects of success in 

 the attempt to obtain coal from the coasts of the Bay of Bengal. 



The whole district, extending from the neighbourhood of Hoosungabad 

 on the Nerbudda river (lat. 23 N. long. 78 e.), on the left or south bank of 

 the river, and extending in a north-easterly direction for a distance of about 

 400 miles to Palamon, thence eastward for 250 miles to Burdwan near 

 Calcutta, and running northward for 150 miles to Kajmahal, exhibits, it 

 would appear, at intervals by no means distant, a continually repeated out- 

 crop of rocks, consisting of sandstones and shales, with occasional lime- 

 stone ; while at intervals a number of beds of coal have been recognised, 

 of variable thickness and value, but all appearing to exhibit evidence of 

 the existence there of a great coal district. 



Commencing again on the flanks of the Garrow mountains, near the 

 Burhampooter, and on both banks of that vast river, we find another, or 

 perhaps a continued, outcrop of similar beds also containing coal, and 

 reaching in a north-easterly direction for nearly 400 miles. The interme- 

 diate plains, whose breadth between Rajmahal and Jumalpore is about 

 100 miles, are chiefly alluvial, and thus it is possible that there exists a 

 vast range of carboniferous strata, reaching for upwards of 1000 miles 

 along the flanks of the Himalaya mountains, — the distance from the moun- 

 tain chain gradually increasing as we advance west>vard, the mountains 

 tending northwards and the outcrop of the carboniferous bed southwards, 

 until finally, the distance between them being upwards of 500 miles, the 

 relation is not easily recognised. The whole of the drainage of the Gan- 

 ges and the Burhampooter occurring, however, in this interspace, we are 

 enabled to connect the geological phenomena in a very interesting manner. 

 Before, however, considering the relation of the discovery thus made to 

 Indian geology generally, it will be necessary to give some account of the 

 nature of the coal in the various places where it has been worked, and the 

 present state of our knowledge on the subject. 



Neighbourhood of Calcutta, 



I. Commencing with the neighbourhood of Calcutta, we have first to 

 consider the Burdwan coal-district, and with this I shall group the Adji 

 and the Rajmahal fields ; all these are on the banks of either the Hoogh- 

 ley or Ganges, or on the tributaries of these rivers. The Burdwan dis- 

 trict has been long known, and a good deal worked. The workable beds «f 

 coal are nine and seven feet thick respectively. They are associated witli 

 sandstone, shale, and a little clay, ironstone, and about six other thinner 

 seams of coal, while other thick beds are mentioned, but their real exist- 

 ence as separate beds is doubtful. There are uow thirteen spots at which 

 this coal is worked, but most of them are surface working. The deepest 

 sinking is 190 fret. The distance to Calcutta is about 90 miles, but the 

 actual transit of coal is nearly 200 miles. There would seem to be a con- 

 tinuous outcrop of the same kind of rocks from Burdwan up the Adji 

 river, and northwards to Rajmahal. On the Adji river the coal has been 

 worked ia more than one spot, and is found to be of about the same quality 

 as that of Burdwan ; but neither of Uiem is considered of nearly so good 

 quality as the English coal. Farther on, at Rajmahal, coal is known to 

 exist, but has notyefbeen much worked. The quality of that which has 

 been obtained does not appear good. 



Palamon Coal Field. 



II. The Burdwan coal-field appears to be connected, by a continuous 

 outcrop, with a district at Palamon, in" which coal has been worked iu no 

 fewer than four places. The coal here is apparently immediately reposing 

 in a valley enclosed by hills of granite, aud is associated with a good 

 deal of iron. There are several beds that are of workable size, but a good 

 deal of the coal is heavy and of inferior quality, and some of it appears to 



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