Congressional Edition Volume 4447 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1902 Excerpt: ... traverse positions of the main stations using the differences as given in the old computations which come from the shore-line coordinates derived from chained distances. The astronomic traverse positions are not comparable in accuracy with the geodetic positions. The latitudes are subject to an error of observation, possibly as much as 0.20" in the result for a latitude, and also to a great uncertainty in position due to station error or local deflection of the plumb line, which is on the average about 3" for points over the whole earth. Pawing from the geodetic to the astronomic latitude there is a lack of homogeneity and a greatly diminished accuracy in the locations of the points. This is very noticeable at South Haven, where the astronomic latitude is 4.11" greater than the geodetic. The matter of correcting the observed latitudes by applying atcorrection for station error was considered, but was not adopted. An examination of the Coast and Geodetic Survey work showing differences of astronomic and geodetic positions on the arc of the thirty-ninth parallel shows that this correction is not constant or even uniformly varying over very restricted areas. It is doubtful, therefore, whether in this work any improvement could le made in the astronomic traverse positions on the east and west shores of Lake Michigan by introducing a correction to the observed values of latitude derived from the differences of the geodetic and observed values in that region, as may be seen by examining the table of astronomic and geodetic latitudes. At the north end of Iake Michigan the station error (A-G) is about--5," while at the south end, as shown by South Haven, it is 4-4." ASTRONOMIC POSITIONS. At a number of places for which the geod...