strides in knowledge and technique of safety work in the last few years. Examples of such possible supplemental regulations may be seen in following pages. MEANS OF PREVENTION IN GENERAL But discussion of legal requirements is not the main purpose of this bulletin. It is not necessary, and less so today than ever before, to depend upon legal requirements alone for the promotion of safety in industry. Consideration for the welfare of employees, and the possibility of reducing economic loss from accidents made definite and specific by the compensation law both. weigh with employers to take measures voluntarily for prevention of accidents. It is to emphasize the seriousness of the particular hazard here considered, and to suggest means of prevention for it in general that is the aim here. Accordingly, in following pages are summarized, from such sources as were at hand, measures recommended by experts which are calculated to prevent injury to workmen by falls in building work. There is every reason to believe that use of measures such as these would prevent a very large proportion of the startling number of fatal accidents due to falls in building work which are now occurring. 66 Scaffolds A recent publication by the Travelers' Insurance Company on Safety Engineering Applied to Scaffolds" gives a complete description of the various kinds of scaffolds and the methods of insuring safety to the men working upon and around them. This is the first comprehensive study of American experience in scaffold construction from the standpoint of safety. Most of the following recommendations are based upon the descriptions contained in this treatise. Scaffolds are roughly grouped into three main classes - pole, suspended and outrigger. Pole or fixed scaffolds are most common. In these the weight is supported by poles or uprights which remain in place until the wall is completed. The bricklayers' pole scaffold utilizes the wall itself for supporting the inner edge of the working platform and hence requires but one row of poles or uprights. Pole scaffolds are used almost exclusively in constructing buildings not over five stories in height and higher ones that have no framework of structural steel. In the construction of high buildings with steel framework swinging or suspended scaffolds are used. Such a scaffold consists of a platform swung by steel cables from the upper part of the steel framework of the building in such a manner that it can be conveniently raised and lowered. Outrigger scaffolds consist of platforms supported upon beams which extend out through windows or other openings in the walls and which are secured to the framework or flooring within the building. Outrigger scaffolds are not recommended when some other kind can be used. POLE SCAFFOLDS Poles or uprights should be straight, straight-grained and free from bad knots and other imperfections. They should be set as nearly vertical as possible to insure stability of the scaffold. They should be set as near the wall as possible. The standard distance from the wall to the poles in a bricklayers' pole scaffold is 4' 6". Poles should not be spaced farther apart than 7′ 6′′ from center to center. They should be fixed at their lower ends to prevent displacement. Cleats for splicing poles should be not less than 114′′ thick and should be wider than the poles. They should overlap each pole not less than 2'. There should be two cleats to every joint or splice and these should be on adjacent and not on opposite sides of the poles. Wherever possible the practice should be followed of breaking joints when splicing poles. Ledgers should be fastened to the inside of the pole. This shortens the span for the putlogs. The vertical distance between ledgers should not exceed 5′2′′. Each ledger should be fastened to each pole with 5 first-class cut nails of large size, preferably 10-penny. Wire nails should never be used for this purpose. one at Putlogs should be close grained, sound and free from knots. There should be at least three putlogs to every plank each end and one in the middle. They should rest on the ledgers as close to the poles as possible. Planks should be carefully selected, straight-grained, sound, and free from bad knots or other defects. The standard size is 2" x 9" x 16'. When such planks are used they should be laid 5 wide. The space between the outer poles and the wall should be filled in as nearly as possible to prevent the falling of men or materials. If the scaffold is properly built there is no necessity for fastening the planks to the putlogs since the weight of the planks and the load they carry is sufficient to prevent their displacement. Planks should not abut on the same putlog. Pole scaffolds should be braced not only to insure stiffness to the scaffold itself but also to prevent the scaffold as a whole from falling away from the building. The poles should also be supported by longitudinal bracing to prevent the scaffold from collapsing parallel to the wall. All braces should be of adequate size and of suitable material. A guard-rail should be constructed for pole scaffolds, so placed that the height from the platform to the upper edge of the rail is 40". These rails should be at least 6" x 1" and should be securely nailed to the side of the poles facing the platform. Two guardrails, the upper one 40′′ high, are preferable to one. A foot-board should project above the platform at least 7′′. It should make a tight joint with the platform in order to prevent materials from falling. Wherever possible a netting of stout wire, having meshes not greater than 11⁄2", should be used along the outer edge of the scaffold platform. This netting should extend from the guard-rail to the foot-board and should be securely fastened to both. SUSPENDED SCAFFOLDS The use of swinging or suspended scaffolds is limited, in new work, to buildings with steel or concrete skeletons. When properly constructed such scaffolds are the most economical and the safest for use on high buildings. The flexibility of suspended scaffolds is an asset in the construction of modern high buildings. The attachment and care of cables should be in charge of men who are skilled in such work. It is quite common for builders to lease scaffolds instead of owning them. In such cases the erectors and caretakers of the scaffolds are men skilled in such work. The platform should be tight enough to prevent the smallest tool from dropping through. It should hang close enough to the building to prevent men from falling through between the platform and the wall. Planks are usually 2" x 9" x 12' or 14'. They should overlap at least 1': an overlap of 2′ is preferable. Workmen should never be permitted to drop objects upon the platform as this practice strains the scaffold much more than does the weight of the objects alone. Suspended scaffolds should be equipped with hand-rails, the upper one, if two are used, being 40" high. It should be securely fastened and strong enough to resist the shock caused by a large man falling heavily against it. Rope is inferior to wood for guardrails. A foot-board, extending at least 7′′ above the platform, should be placed around the platform, inside of the cables. It should fit snugly to the platform at all points to prevent materials from falling through. A side screen, consisting of stout wire with not over 1/2" mesh, should be used on the outside and across the ends of platforms. It should be attached to both guard-rail and foot-board. covers. Because of the presence of workmen above those who work on suspended scaffolds, creating a hazard from falling rivets, bolts, hand tools, etc., such scaffolds should be equipped with protecting Canvas shields placed 3' to 6' above the heads of the workmen are sometimes used for this purpose. Planks or wire mesh are also used. Canvas is most expensive and generally least satisfactory. Wire mesh is perhaps most satisfactory. It permits the free passage of light, weighs less than plank and is not seriously disturbed (as is canvas) by high winds. Where wire is used the mesh should not be over 1/2". Life lines and safety belts for men who go out on thrust-outs to attach or adjust swinging scaffold machines are common in Europe but are seldom seen in this country. OUTRIGGER SCAFFOLDS As already noted, outrigger scaffolds are not recommended where some other form can be used. Where they are used to support workmen and materials they should be reinforced by external struts and braces wherever possible. Sometimes the height of an outrigger scaffold is increased by building a horse scaffold upon it. Such practice is to be avoided if possible. But wherever outrigger scaffolds alone or outrigger and horse scaffolds are used, they should be equipped with guardrails, foot-boards and side screens. Outrigger scaffolds are suitable for use as protective roofs over suspended scaffolds and as catch platforms. It is desirable to have auxiliary platforms at suitable places to arrest the fall of objects from suspended scaffolds or other parts of the building where material is apt to fall. Especially should doorways and passageways be protected by catch platforms when men are working above. BRACKET SCAFFOLDS It is not sufficient for the bolts in the brackets of a carpenter's scaffold to extend through the outer sheating of the building only. They should pass through a board placed across the inside of two vertical studs as well. In laying the platform of carpenters' scaffolds care should be taken to avoid "traps." This can be done by having a sufficient number of brackets so that the boards of the platform will not overlap between brackets. At any rate it is desirable to have enough brackets to prevent the platform from sagging. If necessary two layers of boards should be used instead of one. Guard-rails are seldom found on carpenters' scaffolds though they can be and should be used. Foot-boards are also recommended and in some cases side screens, though the latter are not always essential. PAINTERS' SWINGING SCAFFOLDS The painters' scaffold consists of a light platform made of boards laid upon a horizontal ladder and the whole suspended by ropes from hooks or some other form of support. The hooks used to support the scaffold and to attach it to the building should be sufficiently large for the purpose and should be constructed of firstclass material. Where manilla rope is used it should be of long fiber, at least 1" in diameter, and double lashed at each point of suspension. All ropes should be protected by bagging or wooden blocking at the points where they come in contact with sharp edges. Rope knots should have the ends tied with smaller cord to prevent them from becoming untied. The free rope which accumulates when the scaf |