﻿HOWARD: ANNUAIi PARAIJjAX ' 185 



ventilated, though the readings of the external and internal tem- 

 peratures would indicate that this precaution was not as carefully 

 taken as it should have been. 



In obtaining a full set of observations on a star the wires were 

 first placed perpendicular to the line joining the two stars; then 

 with the movable wire so placed that turning the micrometer screw 

 in a positive direction moved it toward the stationary wire, seven 

 settings were made for distance; then with the wires reversed 

 seven more were made. The micrometer was then turned through 

 180 degrees and a similar set of readings were taken in reverse 

 order. Thus a complete set of observations embraced 28 settings 

 for distance. In reversing the wires and taking what is known 

 as double distance, the error of coincidence was eliminated. In 

 reversing the micrometer it was thought, too, that other errors due 

 to the micrometer, such as unequal illumination of the wires, might 

 be avoided. The hour angle before and after making observations, 

 and the mean for the hour angle of the observation, or the reading 

 of the hour angle at the middle of the observations, were taken. 

 After observing each star, the barometer and both external and 

 internal thermometers were read. The illumination of the wires 

 was adjusted according to the brightness of the star, sometimes 

 red and sometimes white light being used. In setting the microm.- 

 eter wires the screw was always turned in a positive direction. 



This order of work was closely adhered to, and in no case was 

 it changed. 



The intention was to observe as near the meridian as possible, 

 but this procedure was not closely adhered to. In order to begin 

 observations one month before and continue them one month after 

 maximum, it was found necessary at times to observe on rather 

 large hour angles. 



The micrometer light, being controlled by the city current, was 

 not as steady as it should have been and was a source of some 

 annoyance. 



The instrument used was the 12-inch equatorial of the Kirkwood 

 Ol3servatory, Bloomington, Indiana. The objective was made by 

 Brashier and mounted by the Warner & Swasey Company. The 

 micrometer has electric illumination and a position circle of about 

 5" diameter. It was in excellent condition. The wires, whicb had 

 been in place for about a year, were an unusually fine set. Un- 

 fortunately, however, these wires were accidently torn out, and 

 some of the last measures were made with a poorer set of wires. 



