As to the effect of compressed air upon the lungs, and the general construction of the human body, scientific men vary; and, as we have no data from which we could form actual conclusions, we can only arrive at a result by the effect produced upon divers that have come under our notice. The first time a man descends under water he is ordinarily suffering from inherent nervousness, occasioned by the fact of undertaking a thing that has hitherto been unknown to him; consequently there is an increased pulsation and peculiar gasping for breath, and it happens in some cases to be so strong that it would be unadvisable, whilst in that condition, to allow them to descend, but rather, by making them acquainted with the working of the apparatus, and the example of teaching others to descend, to gradually remove the nervous weakness which attends many constitutions. When the nervousness is overcome, it would be advisable that they should descend slowly, swallowing their saliva, and not demanding too much air, resting at times to recover their equilibrium; and if the pressure should cause too great a pain in the heal, by gently ascending a few feet it will gradually remove it, and the descent can be continued. The rule as to coming up depends very much upon the constitution of the diver. A man at all sanguineous should ascend rather slowly; the brain being suddenly relieved from the pressure causes a suden rush of blood to the head, and it may cause unpleasant and serious consequences. We should advise a diver to ascend at a rate of not more than two feet every second-that is, for a stronglyconstituted man. Nor should a diver, for at least two hours before commencing operations, take any food. If any kind of refreshments be require 1, a biscuit, with a small quantity of drink, or anything that will not excite the digestion, may be taken during the operations. Instructions for the Dressing of Diver and the Management of Apparatus. Previous to the diver being dressed, place the fly-wheel on crankshaft, and fix the handles at right angles; oil the pistons with olive or neat's-foot oil, and also the bearings and other working parts; let the pump be wor ed for a few minutes; also pour some water into the cistern to keep the cylinders cool, to prevent the air being heated and thus becoming rarefied. The piping should be laid on the deck, or place from whence the descent is to be made, in a serpentine form, so that the pipe does not kink. Remove the nut on air-nozzle and connect the air-pipe. The attendant should place his finger over the joint at the end of air-pipe, and let the pump work so that he can test the working of the air-pump's valves, and blow out any dust that may be in the pipes. If the water in the cistern becomes heated, it should be renewed. Put on the Guernsey-frock; a pair of drawers and stockings, according to the temperature of the water; place helmet-cushion on shoulders, and tie the outside collar-piece round neck, and round each wrist place one or more vulcanized India-rubber rings. A piece of linen should be placed between the flesh and dress; the cuffexpanders should be used, so that the diver can pass his hand; then put on helmet-collar, place the vulcanized collar over the screws, put on the metal-plates, and screw the dress between moderately tight with the wing nuts; be particular that the four nuts at joints are screwed up at the last. To keep the dress from chafing, put on large over-all stockings and canvas over-all dress, then the boots with lead-soles, and the leather-belt with pipe-holder and knife. The attendant should blow through the outlet valve of the helmet; he can do so by placing his head in the interior, and placing his mouth to the hole where the air escapes; blow strongly; if in proper working order, the valve will vibrate. Connect air-pipe to inlet-valve; previous to doing so, pass it through the pipe-holder on belt, leading it under the left arm of diver; the signal-line to be fastened round the body, and to pass up the front of the right shoulder; the head-piece (without the front glass) can now be screwed on, which is done by one-eighth of a turn. Next attach the lead-weights, one behind and one before; the lines of the back weight pass over the loops on head-piece; the small line should be fastened to the lower corner of weights and round the waist with a slip-knot in front. The diver now being dressed, the air pump must be set in motion; when all is ready for the diver to descend, screw in the front glass. To communicate with the diver when underneath the water by word of mouth, experiments have been made with very satisfactory results, and are now in operation. LIFE-LINE. 1. All right. AIR-PIPE. 1. Sufficient air. 2. According to diver's instructions 2. More air (pump faster). Divers' ladders are generally made of inch rope, with ash-rounds twenty-two inches long, and weighted at the end. Some divers have the ladder only twenty feet long, to the last round a rope with a weight attached, which rests on the bottom; by that means they descend. All now being ready, let the diver descend, and when he reaches the bottom, before he leaves the ladder he must make fast a small leading-line to the ladder. The line should be coiled in the hand with a loop round the wrist, and as he leaves the ladder he lets the rope gradually uncoil, so that if he is any distance off he can find his way back to the ladder if he wants to ascend; but if by accident he loses the line, and is unable to find the ladder, he should make the signal to haul him up. In extreme cases the weights may be thrown off--that is, if he finds himself in any danger, and wishes to rise directly to the surface of the water; but this expedient should be seldom resorted to, as the signal for hauling up can always be given, and with presence of mind many difficulties can be overcome, when hurry and excitement may cause the loss of the diver's life. The diver should seldom go forward; he must generally go backward; and if he meets with anything he must turn round and feel, particularly in the dark; but be careful to return the same way, otherwise he crosses the pipe and line; this precaution is very necessary. If entangled in the rigging, make use of the knife at side to clear himself away. As some men require more weight to sink them than others, we would recommend them to make a shot-belt to buckle round the waist; it may be made any weight the diver may think necessary. On the deck or place from where the diver descends, two careful confidential persons must attend the signal-line and air-pipe; they must attend them with the greatest vigilance, and keep them always moderately tight. If they should feel any irregular jerks which may be occasioned by falls or otherwise, they must haul him up imme liately. The attendants on deck must from time to time give the signal that all is right, and if the diver does not return the signal, he must be immediately hauled up. If the plungers of the air pump or the other motions get slack, they must be screwed up with the spanners sent for that purpose, when the plungers will swell out a little; great care being taken that they are put in the same way as they are taken out, and all other parts of engine put together according to the marks. Always use olive oil for the air-pumps; if not to be got, use well-cleaned neat'sfoot oil. When done working, and the engine is to be put by some time or lifted about, unscrew the plug at the lower edge of the back of the box and draw out the water, to prevent it washing over into the box or cylinders, or splashing the engine, or corroding the cistern if left standing. If the air-pump has been left standing by for any length of time, pour some warm water into the cistern, as it will warm the cylinders and soften the oil round the pistons, and the pump will work much easier. When To examine piston-valves, withdraw piston from cylinder. the valve can be unscrewed to examine cylinder bottom-valves, lean the chest back and unscrew iron-plate on bottom of chest, and then unscrew the valve-bonnets; this arrangement avoids the trouble of removing engine from chest. Be careful that the leather-washers are between the gun-metal joints, so that the air may not escape; also that the joints are screwed together moderately tight. Should the water-proof dress, from constant use or accident, get leaky, it is easily repaired by laying two or three coats of varnish on each side of the seam, rubbing it with the finger as much as possible into the perforations made by the needle, allowing each coat to dry before the next is laid on; the sides of the seam may then be laid . down, and two or three coats applied in the same manner to the channel of the seam, when the prepared strapping (which should have an extra coat laid on and dried) may be immediately applied, and well pressed down with the hand. India-rubber diving-dresses should never be packed away in a wet or damp state; they must be thoroughly dried both in and outside before so doing, otherwise they will mildew, and become so rotten as to be of very little service afterward. Should the dress and pipes be lying by for any length of time, and become hard, place them in a gentle heat, when they will become quite soft. YACHTS AND YACHTING. MODERN TYPES. PARTICULARS OF AMERICAN AND ENGLISH YACHTS. STEAM-YACHTS. AMERICAN AND ENGLISH SPARS, SAILS, ANCHORS, AND CHAINS. NEW YORK YACHT CLUB SAILING REGULATIONS. SELECTION AND CARE OF YACHTS. YACHTS' BOATS, ETC. HANDLING AND CRUISING. BALLOON SAILS. TEMPORARY RUDDERS, ETC. RACING. VARIETIES OF STARTS. EMERGENCIES, ETC., LAYING UP AND REFITTING. QUESTIONS IN FORE-AND-AFT SEAMANSHIP. |