TRANSACTIONS OF SECTION G, 859 
2. The Dymchurch Wall and Reclamation of Romney Marsh. 
By Epwarp Case, Assoc. M.Inst.C.£., FRG. 
Commencing from the time of the Romans, the author traced the history of 
the reclamation and protection of Romney Marsh down to the reign of Henry III., 
when the charter was first granted, and thence to the year 1562, during which 
period the charter was repeatedly confirmed. 
Originally the sea was retained within its limits by a shingle beach; but in 
course of time this natural means of protection failed, and the breaches, which 
occurred in places, had to be closed up by earth banks. As the shores gradually 
wasted these artificial banks had to be extended, until at last they became the one 
continuous embankment, known as the Dymchurch Wall. 
Romney Marsh, depending, as it does, on the Dymchurch Wall for immunity 
from inundation by the sea, lies from 4 to 10 feet below the level of ordinary 
spring tides. Including the adjoining marshes, it consists of some 60,000 acres of 
very valuable arable and pasture land. The problem of sea defence, thus presented, 
is doubtless the most important one that has ever arisen in the British Isles, 
The Dymchurch Wall, as it now stands, is about four miles in length. Its 
top, 20 feet wide, stands 10 to 18 feet above ordinary spring tides. On its inland 
side is an earth slope of 1} to 1; on the seaward side a curved stone parapet, 
6 feet deep, and thence down to the shore level an apron, graded 5 tol and 7 to 1, 
and comprising about 40 acres of stone pitching. Since the early part of the 
eighteenth century it has been persistently threatened by the sea; and on 
numerous occasions it has been subjected to damage, entailing the expenditure of 
vast sums of money on restoration. 
The encroachment of the sea was attributed by the author to the denudation of 
the shore near high water-mark, due to the growth of Dungeness Point, which 
caused the silting up of the bay and destroyed the uniform inclination of the fore- 
shore. ‘The commonly received opinion, that the travel of shore material is 
arrested by promontories, was not accepted by him. He further showed that this 
denudation was hastened by the form of the pitched apron, and by the 
existence of high groynes. The author had arrived at the conclusion, from 
numerous sections, that the natural inclination of a foreshore is elliptical, and 
maintained that this should be kept in view in designing and constructing sea 
defence works. The author’s low groynes at Dymchurch, which have been in 
course of erection during the past five years, are based on this principle. Unlike 
high groynes, they have no scouring effect on the shore, but on the contrary are 
the instruments by which the destructive forces of the sea have been utilised for 
the accumulation of material. The foot of the apron is now protected by a 
covering of sand, a natural inclination of repose exists in the shore, and both 
erosion and encroachment have ceased. 
The author illustrated his paper by a map of the coast-line and three cross 
sections of the shore, 
3. An Instrument for Gauging the Circularity of Boiler Furnaces and 
Cylinders, producing a Diagram. By T. Messencer, A.MI.C.EL. 
‘Hitherto furnaces have generally been gauged for distortion by a diameter 
gauge, which is not so satisfactory as gauging radially, z.c. from a fixed point. 
The Author having this object in view :— 
Firstly, designed that part of the instrument for fixing a pin as nearly in the 
centre of furnace as possible by arranging three telescopic legs at equal angles 
apart, viz. 120°, the points of these legs being caused to radiate outwards or 
inwards simultaneously from the centre pin; so that when the points of these three 
legs rest on the inner surface, and are locked there, the centre pin will always be in 
the centre of these points. To do this in a suitable frame, a centre wheel is 
mounted on the pin, which gears into three other wheels, or segments of wheels, 
