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INTRODUCTION.

consequently were of short duration, and onthat account the invention fell into disrepute.

For a span of 560 feet, and in a situationsuch as that of the Strait of Menai, whereit is as important to maintain a good passagethrough, as to obtain one over, it, a bridgeof this kind is peculiarly suitable. But thestrength of a hanging bridge is active, thatof other bridges passive; and those who areof opinion that a bridge of this kind is to beconstructed to have both these strengths,and also the advantages of insistent bridgesin thoroughfares, may probably find them-selves, when it is too late, in error.

The bridge proposed to be erected overthe Strait of Menai, has been designed uponprinciples different from those demonstratedin this tract, and different conclusions havebeen come to. Upon the same data, bywhich 16 cables have been thought suffi-cient to sustain the roadway and the incum-brances of the proposed bridge, the authorderives that 50 will be necessary. But asa gentleman of eminence has been selectedto erect it, and as his design has beenapproved by a select committee of the

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