Page:The American Cyclopædia (1879) Volume IV.djvu/780

 764 COAST SURVEY raent. Photography is also employed to re- duce the original charts to the scale of the in- tended publications, and a photographic estab- lishment has long been a part of the office. For reducing maps from one scale to another and transferring their outlines to the engra- ving plate, an instrument called a pantograph has been for some years employed. This is a repeating machine composed of a number of arms acting upon each other as levers, with points for tracing and engraving, and mounted upon traverse wheels, for eaae and accuracy of movement. This instrument can be set to any desired scale, representing the proportion which the map to be engraved bears to the original ; and when so set, with the tracing point resting upon the original map and the engraving point upon the plate, if the former be moved over the map, the latter will repro- duce upon the plate an absolutely exact copy of the original on the required scale. The advan- tage gained by dispensing with the old meth- ods of reduction, which required an experi- enced draughtsman, at great expense, together with the greater accuracy resulting from but one operation in reducing from the original to the plate, is apparent when we consider the usual process of drawing, tracing, transferring, and entering by hand. Here are four distinct operations, each liable to more error than the one operation performed by the pantograph. The charts are finally printed at the office, and distributed for sale to agents in the principal seaports. The prices are fixed at very low rates, so as to place a complete set of charts within the reach of every navigator. Provi- sion has been made by congress for the publica- tion of the observations made in the progress of the survey, so as to place the data on which the correctness of the charts depends beyond the possibility of loss, and to submit them to the criticism of the world. Organization. The operations of field work which have been described are carried on simultaneously at many points on the coast. The Atlantic and gulf coasts are divided into nine, and the Pa- cific coast into two sections, each having its triangulation, astronomical, topographical, and hydrographical parties, all working indepen- dently, but upon the same system ; so that, in the end, the whole will form a connected sur- vey from Maine to Texas, and from San Diego to the 49th parallel on the Pacific. Besides these sections, since the acquisition of the ter- ritory of Alaska, the coast survey has added that large extent of coast to its already exten- sive field of operations ; and parties have been at work there regularly, carrying on reconnois- sance, triangulation, topography, and hydrog- raphy, whenever the weather of that stormy region would permit. For conducting these operations there are employed in the coast survey, exclusive of hands and seamen, 94 ci- vilians of different grades, and 1 1 officers of the navy, a number of the latter being required for vessels engaged in hydrography, which are under naval discipline. This force does not in- clude computers, draughtsman, engravers, and clerks employed in the office, all of whom number 93. The whole work is under the control of the United States treasury depart- ment ; while the superintendent directs all the details of the work, governs the movements of the parties, and controls the expenditures. The expense is defrayed from annual appropri- ations by congress, made upon estimates sub- mitted by the superintendent, which from 1853 to 1858 amounted to about $200,000 for the Atlantic and gulf coasts, and about $150,- 000 for the western coast. Of late years, how-. ever, the work has become so much extended, and the labors of the survey so much increased, as to necessitate a much larger expenditure, not a small item in which is the appropriations for new vessels to replace those captured and destroyed during the war, and those which have become worn out by long and arduous service. The progress of the work from year to year is given to the public in the annual re- ports of the superintendent. In these reports not only the results of the year's operations are given, but also the ways and means by which they are obtained. The liberality of congress in publishing and largely distributing these reports has tended greatly to increase the public interest in the work. The investi- gations of the tides, the Gulf stream, the mag- netic force of the earth, and the meteorological conditions of the atmosphere, have an equal bearing upon the interests of navigation and commerce and the sciences connected with the physical condition of the globe. But there are other practical results of the coast survey which have a more direct influence in protect- ing our commerce from the dangers by which it was formerly attended. A consideration of these results will exhibit the advantage of an intelligent application of true scientific prin- ciples in all works of this character. Previous to the year 1844, 300 vessels were wrecked an- nually on our coast, attended with a great loss of life. Of these vessels one sixth were de- stroyed on the Florida reefs. To illustrate the causes which led to this great loss of life and property, it will only be necessary to mention a few of the discoveries made in the survey of the coast. The position of the entrance to Delaware bay, between Cape May and. Cape Henlopen, was found to be eight miles in error. Six dangerous shoals were discovered in one year in the vicinity of Nantucket, lying direct- ly in the track of our European commerce, and of the heavy coast trade between the eastern and southern states. A new channel, with two feet more water than any other, was dis- covered in the entrance to New York harbor. Dangerous shoals were discovered at the en- trance to Chesapeake bay, and along the coasts of Virginia and North Carolina. Innumerable other discoveries of no less importance have been made, but space forbids other mention of them. The few above given are sufficient to