There are, besides the hand-masts, many straight and fair-grown trees that measure less than 24 inches in circumference at the base, which are simply termed spars, or poles. There are also a few pieces occasionally met with that exceed the maximum size of the hand-mast, which are generally dressed approximately to an octagonal form, and then, as at Dantzic and elsewhere, they are called inch masts.
In ordinary specifications for building, it is stipulated the Fir is to be from Dantzic or Riga, as if they were equal in quality; but my experiments on Riga Fir, though not nearly so numerous as those on Dantzic, prove the former to be slightly inferior to the latter. Tables CXXII. to CXXVIII. and CXXIX. to CXXXII. show that the strength of the Riga is to that of Dantzic Fir as follows, viz.:—
| Transversely as | 150 | : | 219 | or, it is | weaker | by about | 31 | per cent. |
| Tensilely as„ | 4051 | : | 3231 | or,„ it is„ | stronger | by about„ | 20 | per cent„ |
| Vertically as„ | 5247 | : | 6948 | or,„ it is„ | weaker | by about„ | 24 | per cent„ |
| Number of the specimen. |
Deflections. | Total weight required to break each piece. |
Specific gravity. |
Weight reduced to specific gravity 600. |
Weight required to break 1 square inch. | ||
| With the apparatus weighing 390 lbs. |
After the weight was removed. |
At the crisis of breaking. | |||||
| Inches. | Inch. | Inches. | lbs. | lbs. | |||
| 1 | 1.25 | .10 | 3.00 | 580 | 524 | 664 | 145.00 |
| 2 | 1.00 | .10 | 3.75 | 707 | 584 | 726 | 176.75 |
| 3 | 1.50 | .10 | 3.30 | 498 | 518 | 577 | 124.50 |
| 4 | 1.50 | .05 | 4.50 | 615 | 534 | 691 | 153.75 |
| 5 | 1.35 | .10 | 3.85 | 677 | 570 | 712 | 169.25 |
| 6 | 1.15 | .10 | 3.35 | 523 | 516 | 608 | 130.75 |
| Total | 7.75 | .55 | 21.75 | 3,600 | 3246 | 3978 | 900.00 |
| Average | 1.292 | .092 | 3.625 | 600 | 541 | 663 | 150.00 |
Remarks.—No. 1 broke a little short ; 2 and 3 with fractures 9 inches in length ; in 4, 3, and 6, the fractures were longer and splintery.
