1840.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



341 



The following appear to me to be {prima facie) the complaints which may 

 be reasonably brought against the commissioners :^ 



1. That having been commissioned to make a survey of the quarries 

 throughout the linitetl Kingdom, they omitted to examine those of Ireland. 



2. That a very superior Irish stone having been offered to them, without 

 charge for royalty, they declined the offer. 



3. That they recommended (among other reasons), "for facility and eco- 

 nomy of conversion," a stone which couM not be procured either in sufficient 

 quantity, or in blocks of a sufficient size. 



4. Tliat on the failure of this quarry, tliey did not go to another which 

 might be considered to stand next in theh report, but to a new quarrj', which 

 has also proved insufficient to supply the required quantity. 



5. That this deficiency of supply has not been made good by application 

 to the quan-y at first so strongly recommended, which is said to contain stone 

 exactly similar to that of the new quarry, and which might be expected to 

 be at the least capable of supplying some stone ; but that two other quarries 

 have been applied to which are not mentioned in the Commissioners' report. 

 In short, that after all the parade of the commission, the supply of stone has 

 been obtained from three several quarries, not one of wliich was recom- 

 mended, nor even its existence hinted at, in the report of the Commissioners. 



This seems a strong case against them, and certainly evinces a want of 

 care in the first survey, and some inconsistency in their subsequent conduct, 

 but I have no doubt that many of the objections are capable of satisfactory 

 explanation. 



The first cliarge, I think, a very dubious one, and rests upon the simple 

 question of whether they were commissioned to visit the Irish quarries or 

 not. 



The second is entirely refuted by the very judicious remarks with wliich 

 you have favoured your readers, and by the fact that in colour and general 

 appearance the stone in question was altogether unsuitable to the purpose. 



The third certainly evinces some want of care. As to the beauty and pro- 

 bable durability of the Bolsover stone, there can be no doubt, hut the thin- 

 ness of the majority of the beds, which is the great objection, is obvious on 

 a sUght examination of the quarry; though the Commissioners, in their just 

 admiration of the quality, might have flattered themselves that by sinking 

 deeper or opening new quarries in the neighbourhood, better blocks could be 

 obtained. It should also be borne in mind that they do not distinctly specify 

 the quarry, hut recommend the stone of Bolsover Mgor and il.i neiyhbonr- 

 hood. 



The fourth objection at first sight appears reasonable, but on consideration 

 I think no one will deny that the stone first recommended having proved 

 insufficient in quantity, Mr. Barry was quite right in adopting that which 

 most resembled it in quality, though he had not seen it when acting on the 

 commission ; being also within a few miles of Bolsover, it may (though by a 

 little stretch of the meaning of the words) be considered to be in " its neigh- 

 bourhood." 



The fifth objection I am unable satisfactorily to answer. I do not see why 

 the Bolsover stone should not have been used, so far as it would go, in sup- 

 plying th^deficiency (which I beheve to be only temporary) in the snjiply of 

 the other quarry. The quality of the Bolsover appears to me to be far su- 

 perior to the Anston and infinitely better than the Steetley (which latter, 

 however, I think is only used internally), and there certainly is stone at 

 Bolsover of sufficient size, though not in large quantities. The circumstance 

 of the Woodhouse quarry being only lately discovered (or rather re-dis- 

 covered), removes the objection of its not being in the report ; but the 

 Steetley and Anston being old and well-known quarries, it certainly looks 

 like negligence not to have reported on them, and like inconsistency to have 

 selected them though not mentioned in the report. One would certainly 

 have expected that before going to these quarries, consistency would have 

 prompted strong measures, such as sinking shafts, opening new quarries, &c., 

 for ascertaining whether suitable steue was not to be obtained on Bolsover 

 Moor. Such measures may have been taken — I only mention this as one of 

 the points which require clearing up for the sake of satisfying the public. 



The most important question, however, after all, is, whether tlie stone now 

 using is of suitable quality. On this question I am not capable of giving an 

 opinion, but will state a few points which have struck me on an examination 

 of the different varieties of stone, with a view to call forth the remarks of 

 more competent judges. 



1. The stone from Mansfield-wood House is not, as has been stated, exactly 

 like the Bolsover. It very strongly resembles it, but differs in having a 

 browner and less brilliant colour, and in having a far greater proportion of 

 black metallic specks, which in some blocks arc minute and clearly defined, 

 in others large and difl'used. This diflference appears to be a great cause of 

 the difference of colour which is observed among the blocks. On the whole, 

 I think the Mansfield-wood House a darker coloured and less beautiful stone 

 than the Bolsover, but still a very beautiful stone. 



2. The question may be asked, what proof have we of the durability of 

 this stone ? In answer to this, I think it may be safely said, that there is 

 every reason to believe that the stone used in the Norman parts of Southwell 

 Minster, and which was supposed to be the Bolsover stone, was, in fact, pro- 

 cured from ilansfield-wood House. A comparison of the stone from the two 

 quaiTies with that at Southwell would, I think, satisfy any careful observer 

 on this head. 



3. The Anston stone does not appear equal to either the Mansfield-wood 

 House or the Bolsover, but is still a good and probably a very durable stone. 



4. The Steetley appears to be a very friable stone, certainly scrai-ciystal- 

 line, but the crystals detached and ill-cemented. It is, I believe, only used 

 internally, but I nmch wonder that the infinitely more beautiful stone of 

 Roche Abbey, which is so eminently suited to internal work, was not pre- 

 ferred. 



What your con-espondent can have discovered in Mr. Bald's very interest- 

 ing papers, to confirm so decidedly the superiority of the Irish limestones, I 

 am at a loss to discover. Mr. Bald's papers only treat of the white limestone 

 of Antrim, which no one even dreamed of recommending for the Houses of 

 Parliament, and which Mr. Bald says should never be used for any buildings 

 where durability is an object. Your correspondent is, perhaps, not aware 

 that Dr. Smith, of whom Mr. Bald speaks witli veneration as the father of 

 English geology, and who, he says, has carefully examined the Antrim lime- 

 stone, is himself one of the Commissioners who have been so much vilified. 



I have the honour to be. Sir, 

 London, Your most obedient servant, 



Sepfember 3rd, 1840. Axother Lover of Fair Play. 



P.S. — It is a question worthy of being investigated, whether magnesian 

 limestones have not a tendency to acquire a dark and gloomy colour by age. 

 The old churches and other buildings on that formation have certainly a 

 gloomy appearance compared with those in some parts of Northamptonshire 

 and Lincolnshire, which arc of oolite. May it not be the case that the 

 lichens which grow on the magnesian limestone are of a dark disagreeable 

 colour, while those which thrive on the oolites are of a white liveher hue > 

 This is rather an important question. 



ON FIRING BLASTS UNDER WATER. 



Mr. Editor, — It occuis to me that a much more simple, and much more 

 efficient method for firing blasts under water, may be obtained, than the 

 method used to break up the Royal George, and a method so simple that it 

 would not require a colonel to superintend. A percussion cap is all that is 

 necessary to fire 10,0001b. of powder as easily as an ounce. Suppose that 

 an air-tigbt compartment at the top of the powder cylinder, to be fitted up 

 with an apparatus similar to the lock of a gun, and a strong spring carrying 4 or 

 5 hammers, to strike as many caps. The cock to set the spring being ground 

 into the side of the box, and fitted with a leather collar ; the trigger should 

 also pass into the box in a similar manner. What would be more easily for 

 the diver after having secured the cylinder strongly to its place, than to raise 

 the spring and fasten a strong line to the trigger ; the line might be of any 

 length, and when strongly pulled would as eft'ectnally fire the blast as a dozen 

 batteries. The caps being inside the air-tight box would be protected from 

 the water and kept dry. 



Mines might thus be fired at the exact instant when they woidd do the 

 greatest mischief to the enemy. 



It is a fact well known to engineers and miners, tliat when it is desirous 

 to detach a large mass of rock by means of several blasts, a great part of the 

 effect is lost by not being able to explode them at the same instant ; but by 

 means of percussion caps a hundred blasts might be fired at the same instant, 

 a very simple arrangement would be sufficient for this piu-pose. 



Would not cannon be also very easily fired by large percussion caps, and 

 struck by a small hammer held in the hand of the person appointed to dis- 

 charge the gun ? 



Those lucifer matches which explode by friction I have used without faihue 

 to fire trains of gunpowder, by merely placing two or three in the slit end of 

 a stick (kept down by a large stone), which on being bent sideways and de- 

 tained in that position by another stick, to which a long line is fastened, on 

 pulling the line the latter stick is withdrawn, and the first carrying the matches, 

 springs straight, the matches scrubbing on the ground or dry stone, explode, 

 and fire the train. 



Should you think these desultory remarks worth a place in your Journal, 

 you will oblige, 



Youi's, respectfidly, 



C. L. Dresse*. 



Commercial Buildings, Leeds, Sept. 4, 1840. 



FELLING TIMBER. 



Sir — Should the enclosed be of sufficient value in your estimation, to en- 

 title it to a place in the Journal, it is at your service. I cut it out of the 

 " New Y'ork Albion" a few years ago, while residing in America. The sub- 

 ject of felling timber is of more consequence to engineers and architects than 

 many of them have supposed, as few would feel desirous of knowing that 

 their labours are not destined in many instances to endure longer than the 

 brief period of their own life, should the dry-rot allow it even that extent of 

 duration. 



I was told by a very skilful mechanic in the city of Philadelpliia, that he 

 had observed in his own experience that timber cut in the winter was in- 

 variably more thoroughly impregnated with sap than at any other time. That 

 as soon as the new wood was at its full growth, say in August, he had found 

 was the best time for felling the timber. 



