Besides the influence on building forms that this stone had, as a universally available and easily worked material, its presence throughout the island had another effect. In spite of abundant rainfall, the stone structure of the island is so porous that there is no natural accumulation of fresh water resulting in an entire absence of springs and streams, so that the inhabitants have been at all times dependent on catching and storing rain water. Thus each roof serves not only its usual protective purpose, but must also serve to catch fresh water. The result is a feature, a marked Bermudian characteristic of roofs immaculate with whitewash and a system of gutters leading to that necessary adjunct of every Bermuda dwelling, "the tank." The form of roofs employed varies considerably. Roofs with gable end and hipped roofs are both used, sometimes in the same building. There seems to be no generally adopted angle of pitch. One finds roofs almost flat and in different degrees of steepness to the sixty degree pitch of some of the outhouses and butteries. The roof surfaces are never interrupted by dormer windows. The roof spans are in no cases large, rarely exceeding eighteen feet, probably governed by the limited sizes of the cedar lumber available for floor beams, but in any case apparently quite sufficient for the needs of the inhabitants. This smallness of span forced a smallness of division in plan, and contributed to the general small scale, a characteristic of island architecture referred to elsewhere. The roof construction consisted of rather light sawn or hewn rafters, either butted at the summit or framed into a ridgepole, and securely fastened to a heavy plate placed on the inside line of the masonry wall. These rafters were tied over interior walls or partitions by long ties at the plate level, but elsewhere by ties placed too high up for structurally efficient service, with consequent thrust at the ends and irregular sagging of rafters. This was done for the purpose of allowing the ceilings of the rooms enclosed to run well up into what otherwise would have been dead roofspace, giving the rooms a surprising height and airiness in spite of low eaves. This form of ceiling, finished either in plaster or wood, gives rise to the not ungraceful, so-called "tray" ceilings, from a fancied resemblance to a serving tray. These, I think, are peculiar to old Bermuda, and Bermudians point them out with pride to visitors. In the carpentry of many of the roofs, construction details of the shipwright rather than the carpenter prevail. Bermudians of the older days were well known for the excellence of their sloops and smaller sailing vessels, and one sees constantly the introduction of shipbuilding ideas in their houses--cedar knees locking at the angles, the timbers serving as roof plates, and tie-beams with the gentle curve or camber of a deck beam, are not infrequent.