Class XX.YJI.]
FLAG-STOXES, PAY1XG-STOXES, SLATE FLAGS, &e.
for that Class, so far as the nature aiul value of theraw material is concerned. At present it is rather inreference to the method of manufacture and relative valuewhen made into pavement, that they have to be con-sidered ; and the reader is referred to the annotations inthe Illustrated Catalogue for some information regardingtiie nature and geological position of several of the moreinteresting among them.
The British paving-stones exhibited may be groupedas follows:—(1.) Yorkshire flags. (2.) Caithness Hags,and Arbroath pavement. (3.) Manx Hags. (4.) IrishHags. (5.) Welsh Hags. (6.) Welsh road material fromPenmaen-mawr ; and (7.) Scotch granite paving. Someroad-stuff is also exhibited in a rough state from severallocalities in Cornwall , but more as samples of what isalready well known and used than illustrations of anynew material or locality.
The Yorkshire tlags— pas ing-stones of great importancein England—are obtained chiefly from a part of the car-boniferous system of rocks developed iu various partsof the county. They are remarkable for size, hardness,and toughness. The only exhibitors of sucli stones on alarge scale are Messrs. Brown, Rusbv, and Booth,of Sheffield (Outside, 29, p. 115',* who are HonourablyMentioned on account of excellence of material and itsadaptability to the required use.
The Caithness Hags and Arbroath pavement are ob-tained from the old red sandstone rock, developed in thenorth and east of Scotland . The former consist of dark-coloured and bituminous schists, slightly micaceous andcalcareous, abounding near Thurso , and remarkable fortoughness and durability. The latter are also ratherdark-coloured, although much paler than the Caithness,and are of very different quality; but they are also de-rived from the lower part of the old red sandstone series.Few Hags are more useful than these, and they are happyillustrations of the excellence of the old red sandstone,generally a barren rock, for at least some important pur-poses. The Jury think it right to <\irect special attentionto Mr. Sinclair's large series of the Forss Rockhill Hagsfrom Caithness (Outside, 13, p. 114), and also to Mr.Carnegie’s series of Arbroath Hags (Outside, 20, p. 115),as in botli cases offering excellent specimens on a largescale, of a very useful material. For this reason theyconsider that both are deserving of Honourable Mention.
The Manx Hags of Quilltam and Cheer (Class I.,151, p. 136\ although not exhibited so largely, areworthy of being alluded to in this place. The following
* The Reporter has found it difficult to obtain definiteinformation with regard to this very important product ofYorkshire . By inquiries made with the kind assistance ofT. Wilson, Esq., of Crumbles House, Leeds , assisted bythe Rev. T. Thorp, he has obtained a list of 92 quarries inthe vicinity of Leeds , Bradford, Wakefield, and Halifax,occurring in a thickness of from five to six hundred yardsat the bottom of the coal measures, and upwards of fifty ofthem supplying flags and landings. The stones known asYorkshire stones may be divided into two classes, calledrespectively grit stones and free stones, the latter beingalso sometimes called delf. Of one of these the BramleyFall Stone (Class 1., 190) is a fine example, being coarse-grained, hard, shining, and containing mica, obtained inlarge blocks but not laminated. The true flags are illus-trated as raw material in Class L, 172, Elland flagstone,&c.; the specimens being fine grained, laminated, andcleaving into Hags varying in thickness from two to three,six. or eight inches. It is stated by Mr. Wilson, that allthe beds from the millstone grit upwards to the Barnsley thick coal are freestones, stratified and often splitting onthe planes of stratification and alternating with beds ofcoal. Between the best flagstones and the millstone gritare some of the coal seams, such as the Halifax coal andthe Halifax soft coal. The flagstones are of course thosebeds most remarkable for their fissile character, perfectevenness of texture, fineness of grain, toughness and hard-ness, and in many cases they can he obtained of very largedimensions. Leeds may be considered the centre of thedistrict supplying the greatest quantities. The quarryingand dressing of these stones requires some practice andingenuit}', and the specimens laid down outside the Exhi-bition Building, and exhibited by Messrs. Brown, Rusby,and Co., are of very good quality.
information has been obtained from the Rev. J. G. Cum-ming (Vice-Principal of King William’s College, nearCastletown, Isle of Man ', who has strenuously exertedhimself to obtain a fair representation of the industrialproducts of the island, and who writes as follows: —“ The black flagstone of Poolvasli ” (found on the southside of the island, near Castletown, and belonging to thecarboniferous limestone) “is a bed whose thickness variesfrom a few inches up to 20 feet. It is too soft to take apolish, and is generally finished with lamp-black and oil,or, in some cases, with French polish. It is very easilywrought, and its durability is well seen in the steps ofSt. Paul’s Cathedral : presented about the commencementof the last century, by Bishop Wilson'.” Messrs. Quilliamand Creer have the lease of the quarries from the Crown,and their works are- in Castletown, on the sea-shore, ata convenient place for shipment. The cost of the plainslabs for hearths, &e., at the place of shipment, is 1 Or/,per square foot. Inlaid with a hard composition inpatterns, as exhibited in Class I., No. 151, the cost for thesame pattern as the national tile is 2s. 3d. per square foot.
Besides the bituminous limestone, there is a flag-stone worked at Spanish Head, not far from Castle-town, obtained from rocks of the older Silurian date.1 hough soft and slightly elastic, and worked withgreat facility, it is very durable, as shown by theRunic monuments in various parts of the island. It hasbeen used for flooring, and is admirably adapted forprison-cells. In addition to these materials, the graniteof the island is considered to be very useful for curb-stones and paving.
The Irish flags exhibited are few, and hardly sufficientto justify any extended description. The principal arethose sent by Mr. Franklin, of Galway , and appear tobe of good quality (Outside, 17, p. 114).
The Welsh paving-stone from Penmaen-mawr is re-markable as being both the hardest and toughest mate-rial for road-stuff that has yet been discovered. It isindeed so hard as to assume a glassy surface after long-continued exposure, and actually becomes dangerous fromthis cause. It is a trap-rock, and appears to be abun-dant. Mixed with less hard material, it might in manycases he a most useful addition to our present resources inLondon .
The specimen of Scotch granite paving exhibited byMr. Sim (Class I., 137, pp. 135, 136) is of excellentquality, and is well put together. It involves a newmode of construction, and is well executed. The ma-terial is adapted to withstand much wear, and the methodof laying down is novel in design, whatever the opinionmay be as to its applicability. The Jury have madeHonourable Mention of the pavement of this exhibitor,as well as that of Mr. Sinclair, as both of them exhibit,to some extent, finished constructions, or working modelsof such objects.
Some beautiful specimens of slate flags from the quar-ries at Festiniog, North Wales (12, p. 114 ', are worthy ofHonourable Mention (awarded a Prize Medal by Class I.),and careful attention, as presenting a cheap and admirablepavement of great beauty, and in slabs so large as toprevent much chance of an irregular surface being pro-duced when much used.
The flags are of fine quality, and have had a severetrial at the Transept entrance of the Building, wheresome millions of footsteps have hitherto failed in pro-ducing any mark of unequal wear.
It is not astonishing that material of the kind we arenow considering, hardly appears except from the variousparts of our own country. From Belgium, Messrs. Zaman(136, p. 1155) have forwarded models of paving-stonesand other manufactured stone of this kind, and cf themthe Jury make Honourable Mention.
A pavement is exhibited by M. Desauges (Trance,1184, p. 1234), manufactured of a stone called Pierre deTonnerre. It is in compartments, tolerably large, andwell executed, the material being well adapted to tiiepurpose. The same exhibitor sends also a chimney-pieceand other works, which will be described elsewhere.*
* Vide page 557.