Also buhr. [Origin uncertain: possibly identical with BUR sb., being so called from its roughness.]
1. a. Siliceous rock capable of being employed for millstones. b. A whetstone.
1721. C. King, Brit. Merch., I. 288. Burrs for Mill-Stones.
1816. W. Smith, Strata Ident., 12. Burs, or scythe stones.
1834. Amer. Jrnl. Sci., XXV. 233. Millstones equal to the best French buhrs.
1879. Shropsh. Word-bk., Bur … a whetstone for scythes.
1880. Jefferies, Gt. Estate, 168. The French burrs … come over in fragments.
2. A siliceous boss or rock occurring among calcareous, or other softer, formations; a harder part in any freestone.
1839. Murchison, Silur. Syst., I. iv. 49. Upright bands of hard sandstone, termed ‘Burrs,’ which cut through the strata.
1865. J. T. F. Turner, Slate Quarries, 16. Circular saws … are … unable to cut through ‘burrs’ … and other hard places.
3. spec. A term applied by quarrymen in Dorsetshire to a soft sandy limestone, with hard silicified bosses, above the ‘Dirt bed’ in the Lower Purbeck series. Also to a harder sandy limestone chiefly made up of comminuted shells, in the Upper Purbeck beds.
1829. T. Webster, Observ. Purb. & Portland Beds, Trans. Geol. Soc., Ser. II. II. Below this is another mass of calcareous stone, considerably softer … it is divided into two by a slaty bed, the upper being called aish, and the lower the soft burr.
1882. Cornh. Mag., 728. Above this, again, we get the soft burr, a lake sediment which envelops and preserves our fossil trunks.
1883. T. Bond, Corfe Castle, 51, note. The stone used is locally known by the name of Bur, and it is perhaps the most durable building stone in England.
4. A partly fused mass of brick; a clinker.
1823. P. Nicholson, Pract. Build., 344. Burrs or Clinkers are such as are so much over-burnt as to vitrify, and run two or three together.
1864. Daily Tel., 2 June, 3/3. The advisability of sinking brick burrs in different parts of the river.
1876. Gwilt, Encycl. Archit., § 1824. Burrs and clinkers are such bricks as have been violently burnt, or masses of several bricks run together in the clamp or kiln.
5. attrib.: see BURR-STONE.
1883. Specif. N. E. Railw. (Alnwick & Cornh. Branch), 58. Price of Dry or Burr Walling.
