APPENDIX. 



I)irc(iioiin to Silcs of Ilensselacr Harbor. 



1. The observatory was placed upon the nortlicriimost of the rocky group of islets that formed our 

 harbor. It is seveuty-six English feet from the highest and northeriiraost salient point of this island, in 

 a direction S. 14° E., or in line with said point and the S. E. projection of the southernmost islet of the 

 group. 



2. A natural face of gneiss rock formed the western wall of the observatory. A crevice in this rock 

 has been filled with melted lead, in the centre of which is a copper bolt. Eight feet from this bolt and 

 in the direction indicated by the crevice stood the magnetometer. This direction is given in case of local 

 disturbance from the nature of the surrounding rocks. 



3. On the highest point of the island mentioned in paragraph 1 is a deeply chiselled arrow-mark Oiled 

 with lead. This is twenty-nine feet above the mean tidal plane of our winter quarters for the years 

 1853-4. The arrow points to a mark on a rocky face denoting the lowest tide of the season; both 

 of these are referred by sextant to known points. 



4. In an enlarged crack five feet due west of the above arrow is a glass jar containing documents. 



5. A cairn calls attention to these marks : nothing is placed within it. 



Extracl from Apjxndix No. X, 2d volume of the Narvalive, pp- 400 — 404, on methods of surwy. 



" It is proposed in the following sketch to give a general account of the methods used in surveying 

 the coasts of Smith's Straits, and of Greenland as far south as Melville Bay. For a large portion of 

 this labor I am indebted to my assistant Mr. Sonntag. 



"It will be seen that the survey conducted by the returning expedition has more claims to accuracy 

 than is attainable by a mere running or flying survey, although the operations wore limited l)y the pecu- 

 liar condition of the party. 



" The means emplo3'ed were, of course, not new ; yet a short and precise account of the methods used 

 to secure as perfect a delineation of the shore line as circumstances would i)ermit may be properly given, 

 with a view to a comparison of results with other surveys of the same region. 



" It may be remarked at the outset that the geographical results of the expedition dei»end altogether 

 for their longitude on the meridian of Rensselaer Harbor. The establishment of this prime meridian 

 was, therefore, an object of great attention. 



"As a general rule, the geographical positions were determined on shore whenever practicable; on 

 some occasions on large floes, which afforded a firm basis for the artificial horizon. On several occa- 

 sions in Smith's Straits, observations for latitude and longitude were made by means of a theodolite. 

 This instrument was provided with a vertical circle of ten inches diameter, and its limb was divided to 

 four seconds : attached to it was a very sensitive level, the value of a scale-division of which had been 

 determined at Washington, and was found to equal 1".13. 



" For latitude a number of measurements of the altitude of the sun's upper and lower limb were taken, 

 commencing about twenty minutes before and ending twenty minutes after the culminations. An equal 

 number of readings of both limbs were taken with the instrument in the direct and reversed position. 

 A screen of pasteboard (irotected the instrument from the direct action of the sun's rays. 



" Observations for time (and longitude) were taken about *J o'clock A. M. or 3 o'clock P. M. 



