of Edinburgh, Session 1877 - 78 . 
685 
weighs 24 oz. It was found about 4J feet down in the boulder 
clay, among the large boulders. 
The other ball was even more spherical, its least girth being 30 
inches, and its greatest 31 inches. Its weight was 54 lbs. It was 
found 10 feet below the top of the boulder clay. 
Professor Crum Brown (Edinburgh University) was so obliging 
as to examine both of these balls for specific gravity and composi- 
tion. He reports that the smallest ball is marcasite or white iron 
pyrites, and that its specific gravity is 4’63. It is entirely of pure 
ore, being apparently unmixed with any other substance. 
With regard to the larger ball, the Professor has sent the follow- 
ing report : — 
“ The fragment of the large round stone which I took for exami- 
nation had a specific gravity of 3 '36. It consisted of a mixture of 
silica (not obviously crystalline) and iron pyrites, in the following 
proportions : — 
“Silica, 52 '3 ) 
__ . , . _ > per cent. 
“Pyrites, 47*7 / 
“ Calculating from these numbers and the sp. gr., it is plain that 
the pyrites must be in the 1 marcasite ’ form, as ‘ pyrite ’ would give 
a considerably higher sp. gr. 
“ The sp. gr. of the whole stone, i.e., the mean sp. gr., was found 
to be 3 ‘28. It cannot, therefore, be a uniform mixture.” 
Mr Murray having kindly offered to examine, microscopically, 
this large stone ball, has sent the following report : — 
“ Challenger Office, Teviot Row , 
May 1878. 
“ Dear Sir, — The microscopic section of the boulder is made up 
of crystalline particles of quartz and marcasite. The marcasite fills 
the interstices between the grains of quartz ; and among the quartz 
there are pieces of mica. (Signed) John Murray.” 
The Convener paid two visits to the excavations in the boulder 
clay at Leith to examine the spot where these two remarkable balls 
were found. He saw the superintendent, who was directing the 
excavations, and also the “ navvy ” who found the larger ball. The 
latter pointed to a whinstone boulder, and said the “ big bullet ” 
was close to this boulder. 
4 x 
VOL. IX. 
