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on the next page. The part of it which is the most interesting is the top
graph, which shows the water-insoluble deposit. An inspection of the
chart will indicate that the dotted line (which is that for the station at
Pool Allotments) was, in the earlier part of the five-year period, well above
that of the other two lines (for the other two stations), but from 1955
onwards the three lines come together much more and in fact in 1957
the dotted line was as often as not below either of the other two lines.
There has in fact been not only a relative but an absolute improvement
in the amount of water-insoluble matter (which is mainly dust
and grit) deposited at the Pool Allotments gauge as compared with that
deposited at the Wearside Road gauge or the Verdant Lane gauge, and
since the Pool Allotments gauge is 300 yards in the prevailing wind
direction from the retort houses at the Sydenham gasworks, it must be
assumed that the improvement shown is due to a marked decrease in
the grit and other insoluble matter thrown out from the gasworks. After
I myself and my predecessors have recorded, on countless occasions
over the last hundred years, complaints with regard to the gasworks,
it is only right now to record that the improvements that have been
carried out there (no doubt influenced to some extent by our complaints)
appear in fact to have been highly effective. The improved
position can be seen perhaps even more readily from the figures in table.