2 RECORD AND RESULTS OF 



cially to regret the scanty material for the determmation of the longitude of Port 

 Foulke. It was also his intention to have the pendulum experiments repeated 

 during the fo.llowing warm season. 



The expedition was supplied with the necessary instruments; among these may 

 be mentioned a prismatic reflecting circle, a Wiirdemann sextant, a vertical circle, 

 and theodolite, all contributed by Prof A. D. Bache; there were also three mean 

 time (box) chronometers, one of these (No. 2007) an eight day chronometer. One ' 

 of the chronometers was purchased from Willard, one hired from Bond, and one 

 was lent free of cost by the brothers Negus ; besides these Dr. Hayes purchased a 

 pocket chronometer from Bond & Son; the pendulum was made by the same firm. 



Hediiction of the Ohservations. — The astronomical data required in the reduction 

 were taken from the "American Ephemeris and Nautical Almanac." 



All mere logarithmic work will be suppressed, but such intermediate results will 

 be given which assist in forming a proper estimate of the value of the observations 

 and of their treatment. 



Separate results are in all cases preferred, unless the increased labor of computa- 

 tion counterbalances the advantage of comparability of individual results. They 

 permit the recognition and consequent rejection of any defective observation in the 

 series, and at the same time furnish the means of estimating or computing the pro- 

 bable uncertainty to which the final result may be subject. This, however, does not 

 exclude the combination of a few readings to a mean reading or the arrangement 

 of individual observations into groups, provided the interval of time is sufficiently 

 short for second clififerences to have any appreciable efi^ect. We may thus combine, 

 in a measure, the advantages of the two methods. 



The refractions have been computed from the tables in Captain Lee's " Collection 

 of tables and formidse, etc." They are Ivory's, and were considerably extended so 

 as to meet the requirements of an arctic climate. I have preferred them to Bessel's, 

 principally on account of their greater facility of application; they give a slightly 

 higher value for very small altitudes. 



Temperatures are recorded on Fahrenheit's scale, and the readings of the barome- 

 ter are noted in inches and fractions of inches. 



Mr. Sonntag had made preliminary computations of his observations which 

 greatly facilitated the present reduction. It is to be luiderstood that the observa- 

 tions were made by him, unless otherwise stated. 



