Scientific American Volume Xxiv., No. 12, March 18, 1871 Part 2

62. A round turn; the cord, a, is pa.s.sed through the bight of the cord, b, over the b.u.t.ton, c, where it is secured by an ordinary knot.

63. Belaying-pin splice. The cord, b, "stops" the pin, e, its end being spliced upon itself, and "served" with yarn; this rope, with its pin, is pa.s.sed through the spliced eye, f of the line, g.

64. Round b.u.t.ton.

65. Joint by a spherical sh.e.l.l, each loop, a and b, being made by ties and splices, and surrounding the sh.e.l.l, c.

66. Belaying-pin, shown separately, before being stoppered.

67. Fastening to shears.

68. Square mooring. When the cable is round the post, A, and the piece, c, without being crossed, it lays in the section 1, 2, 3, 4, 5, 6, 7, and the end is fastened by tying.

69. Wooden sh.e.l.l in section.

70. Crossed fastening. The turns of the cable, pa.s.sing in front of the post, B, are crossed at the back of C, in the direction 1, 2, 3, 4, 5, 6, 7, 8, the end, 8, being secured to the cable.

71. Wooden sh.e.l.l.

72. Double-chain fastening.

73. Las.h.i.+ng for "ram" block, or "dead-eye." The ram blocks, a and b, are strapped by the cords, e, which hold them; the small lanyards, d, pa.s.s through the holes to make the connection, and as they are tightened give the requisite tension to the cordage; the ends are fastened to the main rope. Usually one of these dead-eyes is held by an iron strap to the point where it is required to fix and strain the cordage, which is ordinarily a shroud.

74. Chain fastening.

1'. Simple band, showing the upper side.

2'. The same, showing the under side and the knot.

3'. Tie, with crossed ends, commenced; a turn is taken under the strands, to hold the ends of the cord.

4'. The same, completed.

5'. Bend with crossed strands, commenced, the one end being looped over the other.

6'. The same, completed.

7'. Necklace tie, seen on the upper side.

8'. The same, seen underneath. The greater the strain on the cords, the tighter the knot becomes.

9' and 10' are similar splices to 7' and 8' with slight modifications.

11' shows the commencement of 13', the legs in elevation; 12' being a front view. An ordinary band, made by several turns of a small rope, is lapped round them and hauled taut, and then interlaced at the ends. This done, the legs are s.h.i.+fted into the shape of a St.

Andrew's cross. Thus the las.h.i.+ng is tightened, and, for further security, we pa.s.s the line several times over the tie and between the spars, knotting the ends.

13'. Portuguese knot. This is a las.h.i.+ng for shear legs, and must be tight enough to prevent the spars slipping on each other; the crossing of the two legs gives a means of securing the knot.

14'. For binding timbers; a, knot commenced. Take several turns round the timbers, and fasten the ends by pa.s.sing them under the turns; b, knot completed. The end of a round stick, m n, termed a packing stick, should be pa.s.sed under the k.n.o.b, the cord being slack enough to allow of this. By turning the stick, the turns can be tightened to any extent; when tight, we fasten the longer arm of the lever to some fixed point, by a rope, p q, so that it cannot fly back. Care must be taken not to turn the stick too far, or the rope may be broken. As the timber dries and shrinks, the lever may be used to make all taut again.

THE HARTFORD STEAM BOILER INSPECTION AND INSURANCE COMPANY.

The Hartford Steam Boiler Inspection and Insurance Company makes the following report of its inspections in January, 1871:

During the month, there were 522 visits of inspection made, and 1,030 boilers examined--853 externally and 363 internally, while 106 have been tested by hydraulic pressure. Number of defects in all discovered, 431, of which 163 were regarded as dangerous. These defects were as follows: Furnaces out of shape, 24--3 dangerous; fractures, 47--25 dangerous; burned plates, 29--14 dangerous; blistered plates, 54--10 dangerous; cases of sediment and deposit, 97--18 dangerous; cases of incrustation and scale, 70--24 dangerous.

To show how little attention is paid to the internal condition of boilers by incompetent engineers, we copy the following from a letter of one of our inspectors:

"In one tubular boiler I found sediment in the back end, eight inches deep, and extending forward more than four feet. It seemed to be an acc.u.mulation of fine scale cemented together, so that it was necessary to break it up with a hammer and chisel before it could be removed.

The engineer said _he had cleaned the boilers only three days before_, and objected to my making another examination. This is one of the many cases we find, where the proprietor trusts everything about his boilers to his engineer, supposing him to be reliable."

With such acc.u.mulation of sediment and deposit, is it any wonder that sheets are burned? A careful engineer will understand, if the feed water be impure, that he must blow down two or three inches every day, or oftener, that the sediment may be removed as it acc.u.mulates, and then an internal examination once in two weeks, or once a month, will insure a clean boiler.

Cases of external corrosion, 26--10 dangerous; cases of internal corrosion, 17--5 dangerous; cases of internal grooving, 28--11 dangerous; water gages out of order, 50; blow-out apparatus out of order, 15--7 dangerous; safety valves overloaded, 40--12 dangerous; pressure gages out of order, 54--6 dangerous, varying from -15 to +8 pounds. (We have found several gages entirely ruined from being frozen). Boilers without gages, 4; cases of deficiency of water, 5--1 dangerous; broken braces and stays, 31--7 dangerous; boilers condemned, 2--both dangerous.

Two engineers were found drunk on duty, and promptly discharged. There were 9 serious explosions during the month, by which 99 persons were killed, and 6 wounded. Eighty-seven of the killed were pa.s.sengers on the ill-fated steamer _H.R. Arthur_, on the Mississippi River. Many were drowned, and some burned, but the origin of the calamity was the bad quality of the boilers, which a careless management was unable to detect. The upper and fore part of the boat was blown away by the exploded boilers, and, to add to the horror, what remained took fire.

None of these exploded boilers were under the care of this company.

Five ore-roasting furnaces are in full blast in Nevada.

IMPROVED COMPOUND SPIRAL CAR SPRING FOR RAILWAY CARRIAGES.

Our engravings ill.u.s.trate an improved compound car-spring, which appears to possess all the requisites of a first-cla.s.s spring, combining in its construction extreme simplicity with great strength, and a feature whereby the power of the spring increases with increase of the load, and _vice versa_, so that its flexibility remains nearly constant for all loads.

Fig. 1 is a perspective view of this spring, with a portion of the side of the case broken out to show the interior arrangement of the spiral springs. Fig. 2 is a section of the compressing plate. Fig. 3 is a plan view, showing the arrangement of the tubes which enclose the springs.

[Ill.u.s.tration: POTT'S' SPIRAL CAR SPRING FOR RAILWAY CARRIAGES.

_Fig. 1 Fig. 2 Fig. 3_]

The case is cast in two pieces. Its vertical wall is cast in a single piece, and has at the top a f.l.a.n.g.e or bead extending inwardly, against which the compressing plate abuts when the spring is not compressed, as shown in Fig. 2. A bottom plate completes the case.

The spiral components of the spring are inclosed in tubes, as shown in Figs. 1 and 3. It is not deemed essential that these tubes should be seamless, or that their edges, brought together in bending, should be soldered, brazed, or welded. They act merely as guides to compel the component springs to expand or contract in vertical lines, and need only be strong enough for that purpose.