THE 



PHILOSOPHICAL MAGAZINE 



AND 



ANNALS OF PHILOSOPHY. 



[NEW SERIES.] 



FEB R UAR Y 1832. 



X. Notice of Mr. F ntcha.rd' s gt-adual Progress in the Applica- 

 tion of Iron to the Erection of Bridges. By John White, 



^^^* [With a Plate.] 



TT^HE interest which I feel in recording the advancement of 

 -*■ Science, and the respect which 1 entertain for the memory 

 of my maternal grandfather, Mr. Thomas Farnolls Pritchard, 

 first of Shrewsbury, and then of Eyton Turret, Shropshire, 

 have induced me draw out (as far as i-ecollection and the ma- 

 terials in my possession enable me) a brief account of part of 

 the consecutive designs which led to the first application of 

 cast iron for arches in the construction of bridges ; an applica- 

 tion which not only originated with him, but of which the prin- 

 ciple has subsequently been applied in numerous works of mag- 

 nitude and importance, to tlie great advantage of the public. 



In the year 1773 Mr. Pritchard was engaged in making a 

 design for Stourport bridge, where the Severn requires a 

 water-way sufficient to permit a rise, in flood-times, of 18 feet, 

 and an aperture of at least 136 feet. He originally meditated 

 the construction of a Timber bridge, similar to that which 

 then crossed the Thames at Walton: but not being satisfied with 

 the material, and at the same time being unwilling to employ 

 brick or stone in the buttresses of the bridge in such a manner 

 as would impede the current, he made his first design for a 

 brick bridge on an iron centre, lightened in the buttresses 

 and in part over the arch, by circular perforations, which would 

 allow a passage for the water. 



Apparently dissatisfied with this arrangement, he planned 

 various bridges of these mixed materials; till at length, en- 

 couraged by the patronage of the spirited Iron-masters of 

 Culebrook Dale, he made a design for the bridge now exist- 



* Comnuinicated by the Autlior. 

 N.S. Vol. II. No. 62. Feb. 1832. M \u" 



