or THE CKITED STATES. 337 



lies, the stands of the verniers A, B, C arc inserted in the 

 Journal. The chinip D l)ciiig loose, the teleseopc part, to- 

 getlier with ihe circle, will he turned so us to point the tele- 

 scope upon the object to the Ici't ot the observer, and tlie 

 pointing made by the tangent screw at J). Alier which, the 

 three verniers I), E, Fare read oir, and inserted in the Jour- 

 nal. It is Ijcst to wiite tlieni consecuiixoly in the six lirst 

 columns of tlic journal, heading eacii with its proper letter; 

 the suj)eiscrii)tion of the angle to be measured Ijeing gene- 

 ral, and above all the letters, with any requisite remark or 

 designation of the signal, ^'c. 



Then tlie clatnp at A being opened, the upper part of the 

 instiument without the circle is turned towards the object to 

 the riglit of the ol)server. and being pointed I)y llie tangent 

 screw of the same, the lirst angle of the series of the three 

 vert)iers A, IJ, C may l)e read. 



.After this the clamj) at 1) being opened, and the telescope 

 part, together with the circle, being turned \n\ck upon llie 

 object to the left and pointed by the tangent screw at I), the 

 first angle of the series of I), E, F will be ol)tained. 



In this manner will the observations be continued through 

 as many repetitions as may be desired, paying attenti(jn to 

 concUuie with the same kind of movement with which the 

 ol)servation has commenced, in order to give to i)oth scries 

 the same number of angles. 



In order to keep some account of the progression of the 

 angles, it is also proper to read one vernier, for instance A 

 and I), at each observation, and insert the readings in their 

 l)roper place in the Day- Book. 



From the order of pio^ressing here indicated, the angles 

 will successively follow the oider of the divisions. II' more 

 series are observed, it may he proper to take the second se- 

 ries in an inverse order, or backwrncN on the divisions; as the 

 influence of pressures of screws or friction, t^r. woidd act 

 inversely, and tlie indiscriminate mean correct them as far 

 as possible. 



His also evident, that if the greatest accuracy be aimed at, 



