454 Scientific Proceedings, Royal Dublin Society. 



picked up samples ; from the lot a sample was taken, ground, and 

 forwarded for assay. The return was 2 dwts. to the ton of 20 

 cwt. This, of course, for practical purposes is only a trace, but a 

 very significant one, considering the nature of the rock which had 

 furnished the specimens and their associations. Wishing to render 

 myself an account of the quantity of road metal put down annually 

 by the Corporation of this description, I applied to the Town 

 Clerk, Mr. Beveridge, for such information in this respect as he 

 could afford me. He very courteously communicated the follow- 

 ing details : — 



The Dublin Improvement Act of 1849 came into operation on 

 the 1st January, 1851, and in that year the quantity of Boherna- 

 breena stone used for macadamizing was 14,365 tons. The 

 average quantity used in the 13 years ended 1863 was 17,006 

 tons. The work was then undertaken by a contractor, but was 

 again assumed by the Corporation in 1866. Thenceforth, about 

 15,000 tons on the average were used annually until the extensive 

 paving works commenced in 1879, since when the average has 

 been reduced to about 9,000 tons. The total quantity laid down 

 up to 1888 may therefore be estimated as follows : — 



1851 to 1863, . . . 17,006 tons x 13 = 221,078 tons 



1864 „ 1866, 

 1867 „ 1879, 

 1880 „ 1889, 



16,000 „ x 3 = 48,000 



15,000 „ x 13 = 195,000 



9,000 „ x 9 = 81,000 



Total quantity laid down from 1851 to 1859 = 545,078 tons 



This at 2 dwts. per ton would represent a total amount of gold 

 of 54*537 oz., value about £196*224. Of course it may have been 

 a mere chance that the specimens taken by me should assay so 

 much gold ; but even supposing one-half or the fourth of the 

 quantity it is interesting to note what even such a small quantity 

 in such a mass of rock may represent. It should furthermore be 

 remarked that many of the worked quartz reefs of South Africa and 

 Australia, show in certain parts of the works as small a yield of 

 gold, and that the miner is guided by the assays of the samples 

 from those parts to others more likely to pay. 



There is a further conclusion to be drawn from this assay ; 

 it is that the River Dodder traversing these rock masses, and 

 similar ones higher up in its course, and having received the 



