Falcon in 1912
Plants taken over in the formation of BPCM were carefully assessed and complete schedules of their equipment were drawn up by Works Department. In the case of F. C. Barron's Falcon plant, the schedule is lost, but the accompanying plan has survived. I received a copy courtesy of Chris Down. The version shown here is an approximate rendering of the plan, reconciled with the various editions of the Ordnance Survey maps. It allows a discussion of the layout of this plant.
The Falcon plant was one of the many constructed by George Burge Jr (1832-1911) who was a protégé of I. C. Johnson. Having begun work at the Crown plant, he went on to build the Gillingham plant (1874), and the Phoenix plant (1877), the Globe and Beehive plants (1880). He was by this stage an expert in the construction and operation of Johnson kilns, and used these at the Falcon plant in 1883, with the finance of railway engineer Frederick Cadogan Barron (23/3/1843-4/8/1904). Land was leased, and subsequently purchased, from local landowners the Wakeleys, who were, among other things, operating a brick works at the Overshore quay on Otterham Creek.
The site took only 2.954 acres. It included the existing Overshore Cottages. Part of the quay was taken over for the cement plant, but the brickworks retained tramway access to the wharf. The site included 10 of the 20 existing settling ponds built for the brickworks, and at least some of these were used to store chalk slurry. The chalk quarry was also on Wakeleys land to the south (there is no chalk near the quay), and it appears that the chalk was from the outset slurried at the quarry. The use of the settling ponds as slurry backs suggests that this must, at least at first, have been very thin slurry.
The kilns were of standard design, and arranged in three blocks. The last two kilns (Nos.24 & 25), not shown on the 1906 map, were tacked on to the ends of the second and third blocks. Clinker was evidently moved to the crushers by barrow at ground level.
The details of the plant were partially described in the 1924 schedule, and this plan locates them. Clay was obtained from two zones of the Medway estuary, one on the opposite bank of Otterham creek, and the other between Rainham Creek and the western boundary of Rainham. A wharf-side crane unloaded clay, coal and coke, these then being distributed on 4 ft wide overhead walkways ("gantries"), probably by hand. The two washmills, possibly used in series, were fed with clay from a holding bin and with chalk slurry from an adjacent tank. As was usual with early chamber kilns, there was no storage or blending of the finished slurry - it was made to order whenever a kiln chamber needed to be filled, the slurry being made at a "safe" low lime content. The slurry was pumped to the kilns using a two-throw pump adjacent. Both the mills and the pumps were arranged along the main lay-shaft of the central steam engine.
The kilns were fed with coke from the gantries. The clinker was brought to the crushers and finish mills for grinding. These were also arranged along the main engine lay-shaft. The format of the mills suggests the installation sequence. The plan shows two sets of three flat-stone mills, which presumably were installed concurrent with the first two kiln blocks. Eight chamber kilns would produce around 210 tons of clinker a week. Two out of three stones, running 12 hours a day and six days a week, would grind about 210 tons a week, drawing 75 HP. The remaining mills are two Freeman's Patent Hydraulic Pressure Grinders. These became available in the mid-1890s, and so were probably added with the third kiln block (around 1898). Freeman's mills could be installed on standard stone-mill bottom-driven bases. The 1924 schedule also mentions a separator (not shown). This was probably an Askham separator installed with the Freeman's mills. It is conceivable that these were used as a separate grinding unit, but it is also possible that the Freeman's mills were subsequently used as pre-grinders for the stone mills, as was done at other locations. Also shown on the plan is a tube mill, stated to be FLS, probably a No.12 or 14. These were available from the mid 1890s, and this was probably installed as a finish mill during the early years of the 20th century, in an effort to supply the much finer cements that were by then demanded. This would probably draw around 35 HP.
The main engine in 1924 (it was probably the original) was a 240 HP marine engine made by Earles of Hull. Another engine is shown but not labelled - it may be a double-expansion vertical engine, and might be the original.
Cement was conveyed, probably by screws, to four warehouse stores, again presumably built consecutively. These were simply rooms filled with cement, from which the cement was dug by hand for filling into jute sacks and casks, in an area close to the wharf. As was usual, stocks of packed cement were not stored, but were immediately loaded onto ships.
Casks were always used for medium- and long-distance shipping, and so, in common with other plants distributing by water, the plant had its own cooperage. The large majority of casks were not returned and if a typical 50% of cement was packed in casks, plants of this size needed to make 300 casks a day. The equipment for making this quantity on a semi-automatic basis was considerably more sophisticated than any of the cement manufacturing equipment. In the hoop making shop, iron strip was cut, punched and rivetted into hoops, which were then stretched to a conical section. Stave wood was conditioned, cut to size (24 staves per cask), edged with tongue-and-groove, and the ends were shaped with chime (end-chamfer) and croze (slot to hold the head). The staves were hooped into shape. The heads were assembled from tongue-and-grooved planks, and cut to size, and labelled or printed. This plant, as was common, was driven by a gas engine, fed from a gasifier consuming the tons of wood shavings and chips produced by the cooperage.