Mr. Mellard Reade tells us that this is by no means an isolated case. In the neighbourhood of Blundellsands inspection of brick copings shewed that it was quite a common feature, and he has noted several instances in which the end brickwork and piers have been badly fractured by the force of expansion. In a case where the coping was of blue Staffordshire bricks, the top course in cement and the under course in mortar, a change in length was clearly shewn by the coping being lifted off the wall at each of the two ramps which exist in its length, and the movement was readily measured on the corbel bricks as in the case previously detailed. In this case the lengthening was also a quarter of an inch, and was evenly distributed over a considerable length of coping. Whilst speaking of changes of temperature in their effect on bricks, we may allude to the behaviour of the material in severe conflagrations. A general rule cannot be laid down, because it is customary now-a-days to use fire-bricks for ordinary building purposes which will withstand practically any heat to which they may be subjected. Leaving them out of the question, and referring to ordinary bricks, it may be said that those of an inferior class frequently become cracked all over during a fire, or, it may be, by the sudden cooling after the fire has been put out, or by the sudden lowering of the temperature in them by the continuous action of the fireman’s hose. All the same, the average brick withstands heat far better than any kind of granite, or similar igneous holo-crystalline rock; loosely compacted sandstones and limestones crumble up on the surface, or flake, or may be utterly destroyed when subjected to a conflagration that would not have the slightest effect on bricks. CHAPTER XI. THE MICRO-STRUCTURE OF BRICKS.