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Show 48 of these forms, filled out and with the reductions performed, selected at random from the records of the past field- season. They are given here becausV they may be of use to officers of the Army engaged in the performance of similar duties, who may desire such blanks; and they are valuable as the results of four years' experience in the field, during which the constant attention of yourself and the officers and assistants on the survey has been directed to the perfecting and simplifying the forms and systems of observation and record employed in the various branches of the work. Form I, " Meteorological observations in the field," is for the general meteorological record, upon which is recorded the observations, at stated intervals, upon cistern-barometers and upon all meteorological instruments when assembled daily for comparison. Each individual of the party having meteorological instruments assigned to nim turns them in to the meteorological observer upon his arrival in camp, for comparison, at prescribed hours, with the standards of the party, and the results are entered, with the general meteorological record, upon this blank form as well as in some cases, to be referred to hereafter, upon Forms III and IV. , Blank spaces are left for correcting the readings of the standard barometer and reducing them to 32° Fahrenheit, in order that the errors of the aneroids may be at once determined for use, as explained hereafter in treating of aneroids. This form, as well as Forms III and IV, is bound in convenient shape for the pocket, with instructions as to its use printed upon the flyleaf. Form II is for the clean transcript of the general record ; for tracing out the errors of the various instruments; for the correction of observations for instrumental errors; and, in fine, for the preparation of the observations for final computation of altitudes. This transcript is made in the field, and not only serves as a guard against loss by duplicating the record, but also very materially aids and hastens final results in the office, whither this record is sent as soon as the transcript- book is filled. The necessary instructions as to its use are printed at the bottom of each page, so that no observer of ordinary intelligence will make mistakes in the proper arrangement and grouping of his observations. To guard against errors in transcribing, the executive officer in charge of the party is required to compare the transcripts with the original records, and upon forwarding them to the office to certify that this comparison has been made by him. This blank form, when properly filled out, will then show a continuous record of the comparisons of all the instruments of the party, and give the data for all such hypsometrical determinations as depend upon a series of cistern- barometer readings. In the field, simply the transcript of the record is made upon this form, and all the reductions are made upon it after it has been received at the office. It is bound in quarto size, with stiff pasteboard backs, that the record of each party may be preserved separate, that the data for any of our hypsometric determinations may be readily found, should any one ever wish to recompute them, and to give a firm support for the paper in transcribing upon it in the field, where a table cannot easily be carried. Form III is for the record of such aneroid and thermometer readings as may be taken by individuals not connected with the topographical party proper, at prominent points which may be identified upon the map from the description alone, without the direct intervention of the topographer or his assistants. As can be seen from the form itself, it is intended that each individual shall compare bis aneroid with the principal barometer before leaving camp, and immediately upon his return, and enter the readings of both instruments in this book. Since these comparisons are not usually made at the prescribed hours, they may or may not be entered on Forms I and II, aud although the errors of the aneroids are deduced from those forms, this comparison is imposed only as a further safeguard against loss, that we may have the necessary data for numerous hypsometrical determinations, should even all the books save one be lost. Form IV is the aneroid and odometer record. At each meander- station made by the topographer, including always the stations upon entering and leaving camps, the odometer- recorder enters the time of day, aneroid and thermometer and odometer reading, and the topographer locates the point either by angles between well- fixed points, or from his meander- bearings and measured distances. The aneroid is read both in feet and inches: in feet, for the convenience of the topographer in making his field-sketches; and in inches, for the more accurate determination of altitudes by computation. The altitude of numerous points in the neighborhood of these stations depends upon them for their approximate determination from angles of elevation or depression. Form V is for the transcript made in the field from the " Aneroid readings," ( Form III,) and the " Aneroid and Odometer" books, ( Form i y , ) and for the final computation of the altitudes and profiles deduced therefrom. As the method of treatiug aneroid observations is, as far as I am aware, altogether novel, and moreover, from the facility and rapidity with which the reductions are performed, is likely to be of great use in its application to preliminary surveys for routes of communication, aud iu securing general profiles of lines, the reasons which have led to its adoption, and the method itself, will be more fully described hereafter in this report in treating of aneroid barometers. As with Form II, this transcript must be carefully compared with the origi- |