Carnforth's unusual octagonal slag blocks

There is evidence of square shaped blocks on the original Keer Marsh dump and a wide distribution of round shaped blocks on the Warton sands slag bank but these octagonal blocks are few and very easily missed. They still pose something of a mystery but I'm now beginning to piece together a little more understanding.

Over a long period of extensive research on line, I have found very little reference to octagonal slag blocks. In June 2028 Clive Boulter of the Cumberland Geological Society led a visit to West Cumbria to study the local slag banks from a geological perspective. In his report he mentioned slag blocks as being called "puddings" in the South of the County and "skulls" in the North. He said the block shape ".....evolved from octagonal through rectangular to circular....."   Unfortunately Clive is no longer with us, and I have not been able to find out where that information came from. 

It may indeed be generally true, but the location of these ones near Cote Stones Farm is slightly odd. One would expect to find evidence of octagonal blocks at Keer Marsh, but I did not. I found evidence of square blocks, but I acknowledge that much has changed in the last 100 + years.

Brief references have been found to a tapered octagonal slag bogie patented by "Wood and Wood". Invented by Charles Wood of the Tees ironworks, Middlesbrough in the 1870s.  Charles Wood was also engaged in designing several innovative devices designed to handle blast furnace slag. 

It is said that the earlier round and square boxes suffered from the slag sticking to the sides as it cooled. Wood's patent featured a heavy cast iron bogie body constructed of interlocking tapered octagonal segments. The block being narrower at the top than the bottom helped in removing the cooled slag.   

By pure good fortune, Grace's Guide features a photograph of a blast furnace at the Tees works being tapped for slag....

It is not 100% certain, the box could be round, but I'm calling it octagonal. It fits the description of eight tapered segments and it appears the segments canbe split apart easily enough should the need arise. There appear to be lifting eyes cast in to each plate which would be fundamentally required during assembly of the plates and during tipping of the slag at the dump. 

Why are there only a very small number of octagonal blocks at Carnforth and why are they found only in one localised position?

Those are questions I don't understand and will continue to research. For now, I'd suggest Carnforth might have had some experience of slag sticking to their round boxes. They tried octagonal boxes as a potential solution but found they did not offer any significant benefit. 

There may be evidence of octagonal blocks on the coast at Millom or between Harrington and Workington. That is another avenue to explore in due course.