250 = Review of the Results of the U. S. Coast Survey. 
The finished charts require the work of first class engravers. 
These are so difficult to procure that in spite of the urgent neces- 
sity of the case and the unceasing efforts of the superintendent, 
there were but four first class engravers in the office at the be- 
ginning of the year 1856. Even these were only obtained by a 
special agent sent to Europe for the express purpose. With a 
wise liberality the charts are sold at the lowest possible rates, 
while the gratuitous distribution of the annual reports of the 
Coast Survey gives a still wider circulation to its graphical 
results, 
As the greater number of maps and charts are engraved upon 
copper, and as the softness of this metal renders it impossible to 
obtain more than a limited number of impressions from a single 
plate, a method of reproducing the plates themselves becomes 
indispensable. Such a method is found in the electrotype pro- 
¢ess, which is now applied in the office of the survey upon 4 
very large scale, and which has there received a development 
and a perfection which leaves little to be desired. We believe 
that we hazard little in asserting that as regards the thickness 
and quality of the metal precipitated, the size of the plates, the 
prevention of adhesion between the original plate and that de- 
osited, and the absolute command of the whole process, the 
electrotype operations of the Coast Survey are unequalled in any 
country. ‘ 
It has very recently been found possible to print from ~ 
electrotypes merely folded over the edges of a stout plate 
metal which serves as a support or back. In this manner plates 
of the first quality can be furnished for about one-third of the 
cost of those deposited of the usual thickness. Processes at 
also employed by which small plates can be pieced out in any 
direction and to any desirable size, no line of junction being 
visible between the original and the addition. 
_ The particular apparatus and arrangements 
It was just that an elaborate and complete survey of the Pe 
nomena of the Gulf Stream should be executed by a descend ies 
of Franklin, and it may well be conceived that the pepe 
of that magnificent current, alike interesting from the practi 
and the scientific point of view, have engaged a specia 
attention. In accordance with the direction of Congre 
map exhibiting the state of our knowledge of the ' ulf § ‘on 
should accompany the report of 1853, the work of investiga” 
was pushed forward during that year and results of gree? 
1 share of 
ss that 4 
