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THE riVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[February, 



REMARKS ON THE MORTAR USED IN ANCIENT 

 BUILDINGS. 



WITH OBSERVATIONS AND DIRECTIONS FOR PRAPARING MORTAR IN A 

 MORE PERFECT MANNER THAN THAT NOW IN PRACTICE. 



TuE great perfection to which the arts have attained cannot be 

 denied ; yet on examining the monuments of former ages, of which 

 many are still to be seen in this country, it does appear that the an- 

 cients had some manner of making and using mortar for their buildings, 

 of which our modem artists seem either to be ignorant, or do not 

 choose to put in nractice. Althougli the grand edifices raised under 

 the direction of tne artists of the present age, is a proof that our mo- 

 dem masters, by the study of the monuments left us by the ancients, 

 have been enabled to construct Iniildings vying with their patterns; 

 yet the moderns are still behind the ancients in the construction of 

 buildings with small or promiscuous materials, with that degree of 

 solidity which seems almost to set time itself at defiance. 



There is no doubt little difliculty in raising lasting edifices bv build- 

 ing immense blocks of solid stone, one upon another — but if we say 

 nothing of the enormous expense of this mode of constrnction, even 

 where the materials are to be found in the vicinity, there is some 

 consideration necessary when wuiks which require durability are to be 

 constructed, where no large materials can be readily found. Hence 

 the erection of buildings which may be of the utmost importance in a 

 nationad point of view, as well as to individuals, has to be abandoned, 

 on account of the enormous expense attending the modern plan of 

 construction. 



On a careful examination of many of the old castles in this country, 

 it will be seen that the materials which have been used are of the most 

 ordinary kind; and from the manner in which they have stood for 

 such a long period of time, it does most readily occur, that the mortar 

 \ised in these buildings, has been prepared in a different manner from 

 that practised by modem builders. In fact it will be found that many 

 of these old buildings have been put together with almost every de- 

 scription of stones down to the smallest pebble collected from the bed 

 of the brook, and where no heavy carriages or complicated machinery 

 have been required to construct the most extensive works. 



Our ancient bridges and aqueducts all exhibit specimens of the 

 same kind of construction with very small stones ; depending therefore 

 on the superior manner of preparing the mortar by which these small 

 jnaterials have been cemented together. 



Thus there seems to be an art lost, and in place of endeavouring to 

 recover this art by a series of well conducted experiments, men of 

 genius, and particularly our modem philosophers, seem to have prin- 

 cipally in view to bestow their labours in pushing into the world books 

 filled with abstract calculations which they understand only on paper. 

 These calculations are, however, by far too nice, and it i? much to be 

 feared that few of the writers could be found to reduce them to prac- 

 tice — and as practical men do not understand them, they are useless to 

 the world. It may be very well for the physician to write a learned 

 prescription intermixed with hieroglyphics, to the apothecary who 

 understands it; but alas! the carpenter and builder have neither time 

 nor inclination to enter into the abstruse analysis of the philosopher. 

 Bred to labour from their early youth, it is only from experience they 

 are accustomed to learn ; and it is therefore only from a course of well 

 regulated experiments, described in plain language and simple figures, 

 that the labouring artist's attention can be arrested. 



It would therefore in almost all cases be the means of more rapidly 

 dift'using a knowledge of the useful arts, were our seminaries furnished 

 with the means of exhibiting in some degree of experiment, specimens 

 of the various useful arts. For without experience what is the young 

 engineer who is sent forth to direct the operations of a siege, to raise 

 fortifications, form aqueducts, or construct bridges ? It is clear he has 

 yet to learn from the labouring artificer, the essential parts of his busi- 

 ness; and thus he is sent forth only with the name, to learn from those 

 of inferior station, who are here found capable of giving instructions 

 from experience, where fine theories and abstruse analysis can be of 

 little avail. 



' To return, however, to our ancient buildings, where it appears 

 neither time nor labour was lost in the execution. Many of them seem 

 constructed of little else than rubbish thrown together with an outer 

 coating of small stones, or pebbles from the brook, but built with a kind 

 of mortar which appears to have been thin enough to penetrate the 

 smallest crevices, and to form a solid, compact, nay almost an impene- 

 trable body. And if the ruins are considered with the smallest degree 

 of attention, it will convince us that all the secret of this mode of con- 

 struction, consists in the preparing and using the mortar which has 

 bid defiance to time, and to the tools of the quarrier to remove, after 

 the lapse of ages. Every workman who has been engaged in taking 



down any of our old castles, will testify that he has alwavs been able 

 to remove the stone with greater facility than he could disengage the 

 mortar. 



How differently then must this mortar have been prepared from the 

 very best which is now prepared by our modern builders ; for the 

 latter only dries to fall to dust again when broken into. Another of 

 the grand qualities of the ancient mortar is its being impenetrable to 

 water; and, in fact, the aqueducts for retaining and conveying water 

 which are still to be seen, exhibit no marks of clay or otlier kind of 

 puddle having been used for retaining the water. Therefore, it does 

 appear that aquatic ;is well as other works, were frequently constructed 

 of very small stones, by the builders of former ages, and that they 

 wer« in the practice of forming parts of their buildings into cases or 

 caissons of planking, by which means the mortar when run in amongst 

 the interstices of the small stones, was prevented from escaping. 



It can therefore be most readily conceived how easily a building of 

 great magnitude may be constructed at a small expense, and that of 

 the most durable and lasting kind, of materials with which almost 

 every part of our country abounds, if we are only careful in the pre- 

 paration of the mortar with which these materials are to be cemented 

 together. 



It does not appear that tlie.,apcients used any other ingredients in 

 their mortar than lime, sand, or. calcined earth, such as brick dust, 

 when proper sand could not be procured ; and therefore, ;>s already 

 mentioned, the whole secret seems to be the manner of preparation, of 

 which some explanation will now be attempted. 



It is presumed the fact is well known, that in the burning of lime- 

 stone, the fixed air which it contains escapes, and the stone by this 

 means loses its weight. It has indeed long been the practice to grind 

 or slack the lime immediately after being burned, and by means of 

 mortar mills (where the extent of the works can afford them) to pre- 

 pare the hot mortar for immediate use for building or bedding large 

 materials ; but, it is a fact well known that this kind of mortar (to say 

 nothing of the great expense of procuring itj, would be useless in 

 orduiary buildings, as the weight of the substance in thiu walls com- 

 posed of small materials, would not prevent the burstings, cracks, and 

 sets, which would take place ; nor, from the consequence of blistering 

 which always happens when mortar prepared in this way, is used; 

 . rendering it unfit for plastering either to withstand the action of the 

 weather, or for lining water courses ; because it suddenly dries by the 

 evaporation of its moisture, and consequently, immediately gives way 

 to cracks and shrinking. 



On the other hand lime-mortar after lying a considerable time in a 

 sowered state, imbibes again the fixed air which was discharged in the 

 process of burning, and when carefully examined in this state, presents 

 a kind of transparent, or rather icicle, appearance, which destroys in a 

 great measure the binding quality, and which, in oar changeable 

 climate, rarely or ever has the effect of cementing the building. The 

 latter, however, is the manner in which almost all the lime mortar is 

 most commonly prepared for building, both from a regard to economy 

 as requiring less lime, and also with regard to labour; and, it is more 

 than probable it was by hand labour also, that the builders of former 

 ages prepared their mortar. It is therefore to this principle that ob- 

 servations have been directed, of which the following notice is sub- 

 mitted, and which it is hoped, if properly attended to, will enable 

 those who wish to do so, to prepare and use lime-mortar not inferior 

 to that of the ancients. 



Sower together a quantity of lime and clean sharp sand for two or 

 three weeks before being used ; work this well and turn it aside, and 

 as the proportion of the lime to the sand, will always depend on the 

 quality of the former, all that is necessary is, to take care (in sower- 

 ing), if the lime is of a rich quality, to put one-third less lime into the 

 heap, than it is intended to be built with ; and, if the lime is of poor 

 quality, say only one-fourth less. (^It may here be observed that in 

 general lime of the poorer quality is best for cementing building.) 

 When the lime which has been previously sowered, as before directed, 

 is to be used in the building, or otherwise, it is to be again worked 

 carefully over, and one-fourth of quick lime added in proportions, 

 taking care never to have more in preparation than can be used in a 

 short time ; and this quick lime should be most completely beaten and 

 incorporated with the sowered lime, and it will be found to have the 

 effect of causing the old lime to set and bind in the most complete 

 manner. It will become perfectly solid without the least evaporation 

 to occasion cracks, which can only ensue in consequence of evapora- 

 tion ; and this can only happen from tiie want of proper union between 

 the two bodies. But by mixing and beating the quick lime with the 

 sowered mortar, immediately before it is applied to use, the component 

 parts are brought so near to each other, that it is impossible either 

 crack or flaw can take place. In short beating has the effect of closing 

 the interstices of the sand, and a small quantity of lime paste is effec- 



