606 REPORTS OF THE BUILDING COMMITTEE. 



it more than probable that good marble will be found in the adjacent quarries just 

 mentioned at a considerable lower level than where they are now worked. 



On the northwest branch of Beaver Dam, between fifteen and sixteen miles from 

 Baltimore, and rather more than a mile from the railroad, are Mr. Worthington's- 

 marble quarries, and saw-mill for cutting it into dimension stone. 



The rock in this vicinity is mostly composed of small aggregated crystals, of less 

 size and finer texture than the "alum-marble." 



The old quarry was first visited. It is situated on a hillside, fifteen feet, by the 

 barometer, above the drainage level of the northwest branch of Beaver Dam. The 

 top rock here is not pure, nor even bedded ; but beneath, at the above level, com- 

 mences a marble of snowy whiteness, passing into one with a blue tinge ; see speci- 

 mens 10m> and lObl. This marble spauls with ease and precision, nearly as well on 

 the edge as the bed, and is free to work in every way. This is also the case with the 

 marble taken from Baker's lower quarry ; and indeed all the finer marbles have the 

 same property, unless they are laminated and schistose. The marble here admits of 

 being split out of considerable length, twenty or even forty feet. The face, however, 

 when thus split, is more or less irregular, varying four to six inches or more from a 

 true level surface. 



On the other hand, the facility of spauling enables it to be brought to the desired 

 dimensions with comparatively little labor. The blue-tinged variety quarried here 

 is but little inferior in appearance to the virgin white. Both varieties, though they 

 do not admit of receiving a high polish, like the best quality of Carrara marble, can 

 nevertheless be wrought into very fine ornamental work, with a beautifully sharp 

 arris, as may be seen by the specimen with raised lettering, and that cut into a cap- 

 ital carved by Mr. Parkie, of Baltimore. 



The lower beds are not exposed on the quarry face, but outcropping ledges can be 

 seen in various places around the slopes of the rising ground ; also in the bed of the 

 creek, and everywhere in the bottom, where ditches have been dug two or three feet 

 deep ; all indicating that a region of country of three quarters of a mile square is 

 underlaid by rock of similar character. 



Mr. Worthington has opened a new quarry on a hill about half a mile southwest, 

 and by barometrical measurement 40.8 feet above the level of the northwest branch 

 of Beaver Dam creek, at the stone saw-mill. This quarry is about three quarters of 

 a mile on the east side of the railroad. The upper masses are alone at present 

 exposed. 



They are rather more disposed to crumble than the best quality of the old quarry 

 rock, but it is far superior to the upper beds at that locality, and there is every 

 reason to believe that the best quality of rock is not yet reached ; indeed, probe- 

 holes have been already sunk three feet into the floor of the present quarry, which 

 show that there are solid ledges of white marble of the same texture beneath. 



The hill on which the new quarry is situated is estimated, at the lowest calculation, 

 two hundred yards square ; and it may be excavated for twenty-five feet in depth 

 without being incommoded with water. 



Within the last five years, at least twenty-five thousand cubic feet of dimension 

 stone have been taken out of these two quarries. 



An experienced stonecutter of Baltimore, who has worked a great deal of fine- 

 grained marble, thinks there may be some difficulty in procuring dimension-stone of 

 that quality of greater thickness than twenty inches. The same individual is of 

 opinion that Baker's lower quarry might furnish a material of uniform color, of 

 greater thickness. He has worked both the fine and the coarse crystallized marbles 

 of Baltimore county ; and his experience is, that the fine-grained marble dulls the 

 tool more than the " alum stone," and is more difficult to saw, because, as he expressed 

 it, the fine-grained rock contains most flint. He is, moreover, of opinion that the 

 fine-grained is rather more apt to stain. There is a difference of opinion, however, 

 on these matters. An accurate chemical analysis would throw light on this subject. 

 There is also a difference of opinion as to the presence and proportion of magnesia in 

 the different samples of these rocks. Some contend that the coarse crystalline mar- 

 bles contain most magnesia, and that none of these Baltimore marbles have less than 

 five per cent, of that alkaline earth. These are points which can be alone settled by 

 minute chemical researches. Such analysis would also throw much light on their 

 comparative durability ; since, in the opinion of recent writers on this subject, the 

 greater the proportion of accidental, magnesia, the more liable the rock is to disinte- 

 grate until it reaches a quantity equivalent in proportion to the lime, and then unites 

 with it to form a true dolomite or magnesian limestone; a very durable building 

 material, and the same which was selected, after careful research, for the exterior of 

 the new Houses of Parliament in England. 



