Bricks are burned in clamps and kilns as in England; but it is only in the neighbourhood of the very few coal localities in India that coal fuel can be used; you will generally have to use wood, or in the case of clamps, dried cow-dung and stable litter, commonly called oopla.
At Akra, near Calcutta, there is an extensive Government brickfield, which I advise those of you who are able, to visit; Mr. Hickmott, the superintendent, is a very civil and intelligent man. Hoffman’s kilns have been lately tried, but not very successfully; and I advise you to study the subject, economy of fuel being even more important in India than in England. At the same time, the first cost of construction in this, as in many other instances, must be clearly kept in view; for this cost will have to be added to the cost of your bricks, and as it would not pay to carry bricks far, and Indian distances are long, you cannot afford an expensive construction, however good in itself, which would all fall on the cost of perhaps two or three hundred thousand bricks.
Coloured bricks are nowhere used in India, and their absence is much to be regretted, for they would be most useful both for architectural ornamentation and for floors and similar purposes. The proper clays, on which, as you know, the colours depend, are found in some parts of India; and careful search would doubtless bring to light others;—but here again we are met by the fact that their manufacture requires skill and capital, which are not found on the spot, and would have to be imported. The same remark applies to terra-cotta and encaustic tiles, which would be admirably adapted for Indian use, and would, moreover, stand much heavier transit charges. But the Government cannot be expected to enter the field as manufacturers, and so we must wait, I suppose, for English capital and skill, or for the progress of native enlightenment on these points.
Good ordinary bricks are, however, generally procurable in India, if only proper care be exercised, and a fair price paid for them. The bricklayers require close watching, and often systematic instruction in the all-important subject of bond; for the common native brick is very small, and laid in quantities of mortar with little care about bond; so that native walls are really masses of concrete.
Brick arches are laid, as in England, either in half-brick rings, or, in important works, with the bond carried right through the arch. The natives are very skilful in constructing cheap centerings of dry bricks and wooden soffits, plastered over with mud to the form of the arch, which answer well when your centering is not liable to be carried away by a rush of water. For large arches, whether built with regularly framed timber centres or the common native centres, the French fashion of striking them by means of hollow iron cylinders filled with dry sand, supporting pistons on which the laggings rest, has been largely employed of late, and is much to be commended. You will find it described in Nos. 11 and 24 of the ‘Roorkee Professional Papers,’ as also in the ‘Treatise.’
Masonry made of brick or stone laid in lime mortar is everywhere called pucka masonry. Bricks are, however, often laid in a mortar made simply of thin clay with a little chopped straw in it, and the work is then kucha-pucka masonry. Sometimes sun-dried or unburnt bricks are used, in the case of cheap buildings, for interior walls; or in districts where the rainfall is scant, for exterior walls as well; this is kucha masonry. If well executed, and covered with a leping of clay and cow-dung,—the foundations, tops of walls, and timber framings being finished with pucka masonry—this cheap kind of work answers well in very dry districts, and is cooler than burnt brick.
Tiles are also extensively used in India for roofing purposes, and they are often very badly made. I cannot, however, do more than draw attention to the fact here. You will find plenty of information on the subject in what was once described to me, the author, as “that refreshing work,” the ‘Roorkee Treatise on Civil Engineering.’ The tiles generally used in Government buildings are known as the Goodwyn and Atkinson pattern tile. The hexagonal hollow tile introduced by Colonel Fife for roofing purposes (and known as the Sindh tile), is worth your attention; also the drainage tiles made by Captain Jeffreys for the Ganges Canal. These I mention to illustrate what I have already told you of the necessity of engineers becoming their own manufacturers if they wish to make improvements.
We come now to the subject of Limes and Cements, a very important one in India. Lime is obtained in India from the limestone boulders found in hill torrents, from kunkur, from beds of marl, or rather calcareous tufa, and from limestone in situ. It is burnt with wood fuel, sometimes in the open, generally in conical kilns, and is mixed with sand, burnt clay, or brickdust, and sometimes other ingredients, to form mortar in the usual way. The best lime is that procured from boulders, which when mixed in the proportion of one part lime to two parts of soorkee, or pounded brick, forms an excellent mortar for hydraulic works. Kunkur lime, as a rule, is simply mixed with sand. When lime is burnt with oopla, care must be used in sifting and separating it from the ashes of the burnt fuel, otherwise, of course, its strength will be greatly impaired. Artificial cements have scarcely hitherto been made or used in India. You will find a valuable paper on the relative cost of the manufacture and importation of Portland cement, in No. 294 of the ‘Professional Papers’; also another paper by Mr. Price, describing the manufacture of artificial hydraulic lime at Kurrachee. There can be no doubt of the feasibility of the process; but as a rule, the mortars employed, in Upper India, at least, are excellent, if only proper care be used in their preparation. What is chiefly required is a very quick-setting cement or mortar which, even when used in building in water, shall harden in one or two days. This is much wanted for repairs to canal works, where it is often absolutely necessary to turn on the water before the mortar generally employed has had time to set.
Concrete is not very much employed in India, though it has attracted a good deal of attention lately; and some of the works on the new Sirhind Canal were designed to be built almost entirely of it, such as arches of 40 feet span. Indeed, with an abundance of excellent lime, and a great scarcity of fuel, it seems curious that it has not been more extensively used. Concrete blocks were recommended for the great weir over the Ganges, by the Ganges Canal Committee, to be composed of shingle, sand, and lime; and if proper apparatus be used for testing the quality of the lime, there seems every reason to anticipate economy and good work from such a mode of construction.
Lime is also used in stuccoes and plasters much as in England. Madras is noted for this work, where the very beautiful chunam plaster for interiors of rooms, is as smooth, hard, and polished as marble. Coarse sugar and pounded egg-shells are mixed with these more expensive plasters.