Centres of Gravity of Weights Hung on Cords
Backlit view of a sheet of statics diagrams on balanced weights and cords
This backlit sheet is filled with rows of statics diagrams: horizontal beams and rods carrying weights suspended on cords, each annotated with numerical values. The transcription heads the page with the note that 'below is shown the centres of the weights', and explains that to know the loads borne by the cords holding a weighted beam one must know either the spacing of the cords or the true number of the weights. A lettered figure states that the centres of the weights a and b are equidistant from the cord c. Because this is a transmitted-light exposure, writing from the reverse of the leaf shows through and much of the hand is faint.
On this page
Loads carried by the cords supporting a weighted beam
To find the amounts of weight that the cords sustain, where the beam bearing the weights is fastened to those cords, one must know either the character of the spaces between the cords or else the true number of the weights. The note frames the whole page of beam-and-cord diagrams as a study of how a load distributes to its supports.
Centres of the weights a and b equidistant from cord c
A lettered figure states that the centres of the weights a, b are equidistant from the cord c. It ties the abstract idea of a weight's centre to a concrete balanced arrangement of two loads about a single supporting cord.
Numbered diagrams of weights
Numerous figures accompanied by numbers follow the opening note. The values pencilled beside the beams and cords quantify the weights and the spacing so that the balance of loads can be reckoned.