"Solar" Adjustments 



It is assumed that the transit is in perfect adjustment, especially 

 the telescope level and the vernier of the vertical circle. If there is 

 any index error in the vertical circle, it should be carefully rectified, 

 or an allowance should be made when laying off the declination 

 and the co-latitude. The collimation should be perfect for all dis- 

 tances and the telescope axis should be truly horizontal. 



2. The Polar Axu must be at right angles to the plane defined 

 by the line of collimation and the horizontal axis of the main telescope. 



Level the transit carefully so that the telescope bubble will 

 remain centered during an entire revolution. Turn the solar bubble 

 over either pair of adjusting studs which operate at the base of the 

 attachment. Center bubble with tangent screw and revolve the 

 attachment on the polar axis a half turn. 



If the bubble runs off center, correct half the error with the 

 adjusting studs and the other half with the little clamp-and-tangent 

 movement of the solar telescope. Revolve the attachment a quarter 

 turn so as to make the test over the other set of adjusting studs. 

 If the bubble shows error, correct all of it in the studs, but repeat 

 the operation over both sets of leveling studs until the solar bubble 

 remains centered during an entire revolution. 



In this adjustment the solar telescope bubble has been utilized 

 as a matter of convenience, and for this purpose its relationship to 

 the line of sight in the solar telescope does not enter into the con- 

 sideration. Incidentally, however, the solar telescope bubble has 

 been adjusted to right angles with the polar axis and in this position 

 is parallel with the sight line of the main telescope. 



The little Check Bubble, mounted on the base of the solar 

 standard, should now be adjusted to the center of its run and should 

 remain centered during a revolution, either on the polar axis or on 

 the vertical axis of the transit. Therefore, the Check Bubble should 

 be used for the purpose of rough preliminary setting of the polar 

 axis when the solar attachment is first applied. 



2. To Adjust the Vertical Wire. 



Sight on a plumb line, and if the vertical wire cuts across it 

 diagonally, remove ferrule from diaphragm mount and setting the 

 screw driver blade against one of the washers, tap gently in the 

 direction desired until a coincidence with the plumb line is effected. 



3. To Adjust Horizontal Axis of Solar Telescope. 



While the diaphragm cross is still centered on the plumb line 

 and the adjusting studs have been secured, open the clamp of the 

 solar telescope and, revolving it up and down overlimitations defined 

 by the arch of the standard, note if the intersection of the cross 

 wires passes from one side of the plumb line to the other. 



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