APRIL 11, 1884. ] 
THE GEODETIC WORK OF THE HAYDEN 
AND WHEELER SURVEYS. 
Tue publication of the final results of the 
triangulation of these surveys furnishes the ma- 
terial for a direct comparison between them, 
inasmuch as the two surveys covered in du- 
plicate large areas of country. Fully one-half 
the mountain area of Colorado, and a large 
extent of country in north-eastern Utah and 
south-eastern Idaho, have thus been surveyed 
in duplicate. An examination shows, that in 
the former area no fewer than twelve points 
have been occupied in common as geodetic 
stations, and their positions published by each 
organization. The following are the points in 
question, with the latitudes and longitudes as 
given by each survey, the determinations of 
the Hayden survey preceding in each case. 
The names in parentheses are those given to 
the points by the Wheeler survey. 
STATIONS. Latitude. Longitude. 
37° 34 437.5 | 105° 28’ 55/74 
era Se feo 105 28 57 .0 
37 26 43 .1| 107 3 47 2 
Pagosa . ! } 37 26 87 0 | 107 3 50.0 
Rio Grande Pyramid (Simpson) .} eu ie a 4 1a oe ms a 
38 4 93 .0| 107 27 30 1 
Uncompahgre }| 38 418 .0| 107 27 33 10 
(| 38 25 26 1 | 106 13 15 .7 
Sarxy (Hunts) - )| 38 25 20 .0 | 106 13 18 .0 
38 16 30 .7| 106 51 47 .6 
Agency Knob } 38 16 24 .0| 106 51 54 .0 
‘9 
Wilson (Glacier) || 37 50 21 10 | 10y 69.20 .0 
39 4 51 .0| 107 50 24 .7 
Leon . } 39 445 .0 | 107 50 27 .0 
South River (Macomb) . } oe 34 2 a ate a is 5 
ae 37 21 7 .3| 106 41 35 .4 
Summit (Meigs) . 37 21 1 .0| 106 41 39 .0 
Sneffels (Blaine) {| 38 0 14 .0| tora? 22.0 
37 6 21 .6| 106 37 24 .5 
Banded . 37 6 16 .0| 106 37 27 .0 
The following are the discrepancies between 
the above results : — 
DISCREPANCIES. 
STATIONS. fara aa 
Latitude. Longitude. 
Blanca. 67.5 TZeG 
Pagosa i Oe GL 27.8 
Rio Grande Pyramid 6 .2 2 .8 
Uncompahgre . 5 .0 29 
. > ae 671 2 8 
Agency Knob . Omen 6 .4 
Wilson in ie ee 5 4 % gil 
ti ORR eee 6 .0 2.3 
South River. Gara D3} 
Summit Gace BG 
Sneffels Ay AY Bi 
Banded Bh vet 235 
It will be seen that the discrepancies in 
latitude are quite constant, ranging from 5”.0 
SCIENCE. 
447 
to 6”.7, the Hayden latitudes being in every 
case the greater ; and that the discrepancies in 
longitude are almost equally constant, ranging, 
with the exception of one case, from 17.6 to 
3”.6, the Hayden longitudes being in every 
case the smaller. The comparatively large 
discrepancy in the longitude of Agency Knob 
is explainable by the fact, that, from most 
points of view, this station presents an ill- 
defined summit. The constancy of these dis- 
crepancies points to the fact, that they are in 
the main due to station-error, as is unques- 
tionably the case. The Hayden work was 
based on Denver as determined astronomically 
by the U. S. coast and geodetic survey, while 
the Wheeler work depends upon Colorado 
Springs as determined by the Wheeler survey. 
The relative station-error of these two places 
has not been determined directly, but cannot 
fail to be considerable, owing to the difference 
in their surroundings. 
Assuming that the difference in station- 
error between Denver and Colorado Springs 
is, roughly speaking, equal to the average 
difference between the Hayden and Wheeler 
work (leaving out Agency Knob), —i.e., 57.9 
in latitude, and 2”.7 in longitude, —and cor- 
recting one of the two above sets of results 
therefor, the discrepancies between them be- 
come as follows : — 
DISCREPANCIES. 
STATIONS. 
Latitude. Longitude. 
~“ 
“ 
WwiohaHnnwowia 
~ 
N 
WOOHOO Rb 
Blanca 
Pagosamiewssin so 
Rio Grande Pyramid 
Uncompahgre . 
Ourayeaen 
Agency Knob . 
Wilson 3 
Leon . , 
South River 
Summit . . 
Sneffels . . 
Banded . 
ooocoqocoqoocoocoeco 
ceococowocoocr 
The mean of these differences in latitude is 
but 0”.55, and in longitude, with the excep- 
tion of Agency Knob, but 0”.41. 
The area surveyed in duplicate north of the 
Union Pacific railroad in north-eastern Utah 
and south-eastern Idaho does not show quite so 
close accordance in results. The Hayden work 
here depends upon the astronomical determi- 
nation of Salt Lake City by the U.S. coast 
and geodetic survey, and is checked upon the 
determination of Ogden by Wheeler’s survey, 
upon which the Wheeler work rests. This 
check shows little or no difference in station- 
error between the two astronomical stations. 
The following are the positions of five points 
