316 Proceedings of the Royal Society 
has been most satisfactory, as proved by the fact, that previous to 
their construction the depth on the bar never exceeded 11 feet 
and frequently fell to 8 feet ; whereas, according to the last ac- 
counts from Sir Charles Hartley, the depth for the last five years 
has never been less than 15 feet, and has often been as much as 
17J feet. 
It is obvious, however, that as the Danube must continue to 
bring down an enormous mass of detritus, so, in course of time the 
works which have proved so successful must be extended — an 
event which has been fully anticipated by its projectors, and in 
this respect we find an interesting difference between such works 
as the Danube piers and the harbour works of this country, for 
here the object being to prevent the waves from acting on the bot- 
tom, the engineer extends his works out into a depth of water 
where there is little or no disturbance of the bottom, and if this is 
once secured he may calculate on the increased depth of water re- 
maining permanent, whereas, at the Danube the piers must be 
projected to keep pace with the gradually increasing delta at the 
river’s mouth. 
2. Remarks on two Pyramid Papers in the last published 
Number of the “ Proceedings” of the Royal Society of 
Edinburgh. By Prof. Piazzi Smyth, April 20, 1868. 
On the 10th of March last I had the honour of receiving, in the 
usual course of publication, a copy of the 75th Number of our 
Society’s Proceedings. 
Within that Number’s few pages, there are no less than two 
distinct essays, mainly, if not entirely, on “ the Great Pyramid , 
“ and my views respecting it .” 
Both these essays, though by able and ingenious men, are yet 
unfortunately based to such an extent on needlessly imperfect data, 
that the superintending Secretary might have justifiably returned 
the MSS. to their respective eminent authors, with suggestions for 
improvement in the improvable particulars, before publishing them 
under the auspices, and at the expense of the Society. 
This course, however, was not followed ; and the words of friendly 
advice, which might before have been offered in private, require 
