Summary
Runnels, created between 1794 and 1815, extended southwards by 1832, which are formed of shaped blocks laid crossways, and narrow long kerbstones set above at the sides to contain the water flow. The runnels continue along both sides of the road from a point opposite Brook House, 10 Trumpington Street, northwards on both sides of the road to the point where Trumpington Street is joined by Mill Lane on the west side, and Pembroke Street on the east. Water is permitted to run freely along them between April and October.
Reasons for Designation
The Trumpington Street runnels of Hobson's Conduit are designated at Grade ll for the following principal reasons:
* Substantially intact runnels for town water supply created between 1794 and 1815. The were extended southwards to their present extent by 1832.
* High technological interest relating, as they do, to a water supply sytem of undoubted historic significance in a national context.
* Rare if not unique survivals in a major urban centre.
* Group value with Hobson's Conduit head and buildings on Trumpington Street
History
Hobson's Conduit was installed following a Deed of 1610 to conduct water from Nine Wells in order to scour and cleanse the King's Ditch and to do the same for colleges. There is no evidence that it was initially intended to supply drinking water, although it subsequently was used for this purpose and to supply water for various ornamental and practical purposes to Christ's, Emmanuel, Pembroke and Peterhouse Colleges and the Old Botanic Garden.
Details
The conduit head originally stood on Market Hill but was re-erected in its present location on the corner of Lensfield Road and Trumpington Street, in 1856. There were four channels from the conduit head, three of which existed in the C17. One channel continued east along what is now Lensfield Road and St Andrews Street, its open watercourse clearly visible in Horraden's map of 1810. A second flowed north eastwards to the fountain in the Market Place although this was cut off near Downing Street in 1970 when the Lion Yard was redeveloped. A third flowed in the open behind the first three houses in Trumpington Street, ran through a brick culvert behind Cromwell Lodge and then emerged in the open at Addenbrookes (a stretch abandoned c. 1905) before being piped under the pavement of Trumpington Street. All these channels, with the exception of a small section in St Andrew's Street, are now piped or run in culverts with no evidence above ground except for manhole covers and plates.
In the C17 a Hobson's Conduit channel would appear to have taken the route via Addenbrookes before continuing down the middle of Trumpington Street. It then turned off to the left down Mill Lane at the gate of Pembroke College and flushed out the King's Ditch with a subsidiary channel round the back of Pembroke College, falling into the King's Ditch to the west of Free School Lane. There is a description of the watercourse in 1794 in Henry Gunning's reminiscences, published shortly after his death in 1854:
'along the whole front of Pembroke College was a watercourse that divided the street into two very unequal parts, the west side was by necessity the carriage road but was only one-third the width of the road which adjoined the college and was appropriated for foot-passengers. The sides of the channel were boarded and it was crossed by two very narrow bridges; one opposite the Master's Lodge and the other opposite the gate of the college.'
When the change to the present arrangement of twin runnels occurred is not known exactly. In 1789, it was agreed that the town should widen Trumpington Street by taking in a strip of the street frontage to which Pembroke College had a claim which suggests that even before 1794, works to the street were envisaged. Custance's map of 1798 fails to distinguish either the channel or the two runnels but it is likely the change would have taken place by then, probably soon after 1794. The two runnels were definitely substituted before 1815, the date of Ackermann's engraving of Pembroke College which shows them.
W. D. Bushell refers to the runnels originally welling up opposite the north end of Addenbrooke's Hospital front rather than the present location in front of Brook House, citing as evidence an unnamed plan of 1832. There is some evidence that may relate to this on the ground where the kerbstones to the N of Addenbrookes are broader than those to the S (see figs. 7, 8) although these larger stones may simply be a result of subsequent resurfacing of the road or pavements. Certainly when the conduit was surveyed in 1886, the resulting plans showed the present arrangement of the runnels commencing at Brook House. The conduit works have subsequently undergone minor alterations, the runnels being piped under side roads.
