(11.) Economy; as natural forces can be used, thus saving labour, and it can be laid from 1¹⁄₂ to 2 inches thick only.
(12.) Having sawn edges, the joints are expeditiously and well made.
(13.) Its whole surface wears evenly.
The following table was compiled by the well-known firm of Kirkaldy, by direction of Mr. Tarbotton the Borough Engineer of Nottingham, in order to ascertain the resistance to a gradually increased bending stress upon Yorkshire flagging as compared with Caithness.
Yorkshire.
| Test No. | Weight. | Dimensions. | Ultimate Stress. | |||||
|---|---|---|---|---|---|---|---|---|
| Length. | Breadth. | Thick- ness. | ||||||
| K | lbs. | inches. | inches. | inches. | lb. | |||
| 1918 | 184 | 36 | 24 | ·07 | 2 | ·46 | 4 | ·744 |
| 1919 | 163 | 36 | 24 | ·03 | 2 | ·22 | 3 | ·398 |
| 1920 | 107 | 36 | 23 | ·90 | 1 | ·50 | 1 | ·459 |
| Mean | 151 | 36 | 24 | ·00 | 2 | ·06 | 3 | ·200 |
Caithness.
| Test No. | Weight. | Dimensions. | Ultimate Stress. | |||||
|---|---|---|---|---|---|---|---|---|
| Length. | Breadth. | Thick- ness. | ||||||
| K | lb. | inches. | inches. | inches. | lb. | |||
| 1921 | 215 | 36 | 24 | ·06 | 2 | ·59 | 17 | ·274 |
| 1922 | 178 | 36 | 24 | ·05 | 2 | ·15 | 12 | ·711 |
| 1923 | 114 | 36 | 23 | ·90 | 1 | ·38 | 6 | ·211 |
| Mean | 169 | 36 | 24 | ·00 | 2 | ·04 | 12 | ·065 |
By which it appears that the balance in favour of Caithness flagging is 8·865 lbs.
The objection to this style of flagging is, that however varied the sizes of the stones selected may be, as they have sawn edges and are very hard to cut with a chisel, a difficulty sometimes arises in finishing rounded corners of footpaths, and against uneven frontages of shops or buildings abutting on the footpath; this is especially the case in old towns.