BRIDGES. 



(as the waters gain in depth what they 

 lose in breadth,) otherwise the current 

 may wash away the foundation, and en- 

 danger the piers: to prevent this, they 

 sometimes diminish the current, either by 

 lengthening its course, or by making it 

 more winding"; or by stopping the boitom 

 with rows of planks, stakes or piles, 

 which break the current. It is also re- 

 quired, that the foundation of bridges be 

 laid at that season of the year when the 

 waters are lowest : and if the ground be 

 rocky, hard gravel, or stony, the first 

 stones of the foundation may be laid on 

 the surface ; but if the soil be soft sand, 

 it will be necessary to dig till you come 

 to a firm bottom. For the particular mode 

 of constructing stone bridges, the reader 

 is referred to the latter end of the article 

 BUILDING. 



The triangular bridge at Croyland, in 

 Lincolnshire, England, which was erect- 

 ed about the year 860, is said to be the 

 most ancient Gothic structure remaining 

 entire in the kingdom. There are two 

 circumstances in the construction of this 

 bridge which render it an object of great 

 curiosity. First, it is formed by three 

 semi-arches, whose bases stand in the cir- 

 cumference of a circle, at equal distances 

 from each other. These unite at the top ; 

 and the triune nature of the structure 

 lias led some to imagine that it was in- 

 tended as an emblem of the Trinity. Se- 

 condly, the ascent on each of the semi- 

 arches is by steps paved with small stones 

 set edgeways, and is so steep, that none 

 but foot passengers can go over the 

 bridge : horsemen and carriages fre- 

 quently pass under it, as the river in that 

 place is but shallow. For what purpose 

 this bridge was really designed, it is diffi- 

 cult, if not impossible, to determine. Uti- 

 lity, it is obvious, was one of the least mo- 

 tives to its erection. To boldness of de- 

 sign and singularity of construction it has 

 more powerful claims ; and these quali- 

 ties it must be allowt d to possess, in as 

 great a degree as any bridge in Europe. 

 Although this bridge has been erected 

 so many centuries, it exhibits no marks of 

 decay. 



London bridge is in the old Gothic 

 style, and had twenty small locks or arch- 

 es; but there are now only nineteen 

 open, two having been lately thrown in- 

 to one in the centre. It is 940 feet long, 

 44 high, and 47 clear width between the 

 parapets. The piers are from 15 to 35 

 feet thick, with sterlings projecting at 

 each side and end, so that the greatest 

 water-way, when the tide is above the 

 sterlings, is 545 feet, scarcely half the 



breadth of the river ; and below the ster- 

 lings the water-way is reduced to 204 

 feet, causing a dangerous fall at low wa- 

 ter. London bridge was first built with 

 timber in the reign of Ethelred, between 

 the years 993 and 1016 ; it was repaired, 

 or rather rebuilt, of timber in 1163 ; and 

 the present stone bridge was begun un- 

 der King Henry II. in 1176, and finished 

 under King John in the year 1209. It is 

 probable there were no houses on the 

 bridge for upwards of 200 years, since we 

 read of a till and tournament held on it 

 in 1395. Houses were erected upon it 

 afterwards, but being found a great in- 

 convenience and nusiance, they were 

 removed in 1758, the avenues to the 

 bridge enlarged, and the whole made 

 . more commodious : the two middle ar- 

 ches were then thrown into one, by re- 

 moving the pier from between them. 

 The expense of the repairs amounted to 

 above 80,000/. 



The brklges of Westminster and Black- 

 friars, over the river Thames, at London, 

 are among the finest structures of the 

 kind in Europe. The former is 1220 feet 

 long, and 44 feet wide, having a commo- 

 dious broad foot-path on each side for 

 passengers. It consists of thirteen large 

 and two small arches, fourteen interme- 

 diate piers, and two abutments. The 

 length of each abutment is 76 feet ; the 

 opening of each of the smaller arches is 

 25 feet ; the span of the first of the large 

 arches at each end is 52 feet, of the next 

 56 feet, and so on, increasing by four feet 

 at a time to the centre arch, the span of 

 which is 76 feet. The two piers of the 

 middle arch are 17 feet wide ; and the 

 others decrease equally on each side, by 

 one foot at a time, every pier terminating 

 with a salient right angle against either 

 stream. The arches are semi-circular, and 

 spring from about the height of two feet 

 above low water. The breadth of the 

 river in this place is about 1220 feet, 

 and the water-way through the bridge 

 amounts to 870 feet. The bridge was be- 

 gun in 1738, and opened for passengers 

 in 1750, at a neat expense of218,800/. It 

 is constructed of the best materials, and 

 in a neat and elegant taste ; but the arch- 

 es are too small in proportion to the 

 quantity of masonry. 



Blackfriars bridge, nearly opposite to 

 the centre of the city of London, was be- 

 gun in 1760, and completed in ten years 

 and three quarters, at a neat expense of 

 152,84Q/. It is an exceedingly light and 

 elegant structure ; but, unfortunately, the 

 materials do not seem to be of the best 

 kind, as many of the stones in the piers 



