BRICKWORK. 925 



do not set in a moist place, nor do they ever attain any great 

 degree of hardness. 



Moderately hydraulic hmes will set in a permanently moist 

 position, and eventually become as hard as a soft stone, whilst 

 eminently hydraulic limes will set even in water, and possess 

 the characteristics of hard stone. 



Sometimes fat limes are artificially rendered hydraulic by 

 moderately calcining an intimate mixture of fat lime with the 

 same quantity of clay as is found incorporated with hydi'aulic 

 limestones, and this is a practice which might be more 

 extensively employed in districts possessing only poor limes. 



Although fat limes attain a fair degree of hardness when 

 exposed to a dry atmosjjhere, yet I have found mortars 

 composed of such limes to be soft in the centre of a wall. 



I have also made concrete briques of fat lime mortar, and 

 after the composition has hardened I have buried it, and then 

 after the lapse of a few months dug it up, only to find the 

 concrete again hi a plastic state. On one occasion I had to 

 make additions to an important building in Launceston 

 which showed signs of extensive settlement. The founda- 

 tions were of lime concrete, but when excavations were made 

 I found metal, sand, and earth, but could discern no trace of 

 lime, for it had dissolved and had been carried away by 

 drainage. 



The advantages of a mortar-mill in thoroughly grinding 

 and incorporating the various ])arts of mortar is very great. 

 I wish its use were more general, for then we should not 

 only get stronger mortar but also a less lumpy material, which 

 would ensure better and neater brick-work. 



Ancient Roman mortar has gained a reputation for strength 

 and durability, and not without reason, for Roman mortar is 

 now frequently found which is more difficult to break than 

 the bricks and stone it formerly cemented together. Romans 

 usually burnt lime on the spot where it was to be employed as 

 moilar, then used it whilst it was fresh and hot, and often 

 mixed it with pounded biicks instead of sand. 



Laws of Construction. 



Having now briefly considered the two great constituents 

 of brick-work, it may be well to determine their legitimate 

 office. 



Constructionally speaking, brick architecture is essentially 

 a style of arches, for, as I have already said, its component 

 parts are too small for lintels, although they are eminently 



