A PrExVDIX. 



49 



" 'I'hc priiieip;il puiiils ol' the coast luivc thus liccoiiic known, ciilu-r li\- direct observations of huitiulc 

 and longitude, I)y hititudc and soKar bearing, or by the intersection of two azimuths, aeeording to 

 metliods explained above. 



" The filling in of the minor or secondary points remains yet to be explained. The po.sition was 

 generally obtained by solar or compass bearings and estimated distances. In regard to the solar bearings, 

 it may be remarked that their frequent application rendered the construction of a table of douljle entry 

 for every degree of altitude of the snn from 5° to 3fi°, and for every degree of angular distance from 

 10° to 125°, quite an acceptable improvement in facilitating the reduction. In regard to magnetic 

 bearings, it is to be remarked that they were taken with a pocket-compass, the face of which, divided into 

 degrees, was fastened to the bottom of the box to allow the needle free play. The magnetic declination 

 (variation of compass) observed with this instrument at different times at the same place seldom differed 

 more than three degrees, while on the contrary, other compasses, with the card fastened to the needle, 

 would remain stationary in any position in which they were placed, in consequence of the small hori- 

 ■ zojital force in the region traversed. Care was taken to keep the compass perfectly level, and in .sighting 

 the eye was kept directly over the north end of the needle. 



"The estimation of distances of intermediate points was the only thing loosely obtained; but it must 

 be remembered, however, that these distances were always checked by means of astronomically determined 

 positions, and hence, no error of this kind, although they were of frequent occurrence, could be propa- 

 gated. Distances estimated at the same time have in some instances received a proportionate correction 

 obtained from the check of any single line directly from comparison with astronomical data. At other 

 times, distances paced were found to agree remarkably well with their distance astronomically determined. 

 In this way a journey undertaken in March, 1854, was found correct to within one-thirtieth of the whole 

 distance travelled over in six days. 



" The survey of bays and harbors was conducted in the ordinary way, by means of a base-line measural, 

 either with a cord properly stretched or by pacing. Angles were then measured at each extremity, and 

 occasionally another point was determined trigonometrically. The head-lands, prominent bluffs, and 

 islands for these maps generally were determined astronomically. * * * * 



* * * " The whole survey, made as explained above, embraces that portion of the coast 

 north of Capes Alexander and Sabine. That portion of it included between Cape Alexander and Uper- 

 navik, which was in revision of the work of our English predecessors, as laid down in the Admiralty 

 charts, was made during the escape of the party in boats. For the greater portion of this lalwr I am 

 indebted to Mr. Sonntag. E. K. K." 



rUIiLISIIED BY THE SMITHSONIAN INSTITUTION, 



W A S H I N r, T N CITY, 

 .MAY, IS 60. 



