440  Hough—Description of a Printing Chronograph. 
in the method of regulation, printing, etc. The fast moving 
train was used to propel the integer seconds and minute type 
wheels, dispensing with the auxiliary movement; but the dis- 
turbance of its motion was considerable, especially at the end 
of every minute, when it had double duty to perform. 
The saving of time and labor by the use of a printing chrono- 
graph is very considerable. At the lowest estimate, it does 
work equivalent to the labor of one person where three are em- 
ployed at the same time. In our zone work in former years, 
when the zone extended two hours in right ascension, it usually 
required the labor of two persons a whole day to convert the 
chronographic records into numbers and copy them on the 
blank forms. With the observations printed, this labor is 
wholly dispensed with; since the “mean” is at once deduced 
from the printed records. 
The machine is readily adjusted to indicate the same num- 
bers as the clock’s face, the type being so set as to print zero- 
hundredths when the pendulum is at its lowest point, where the 
magnetic circuit is completed. In the construction of the appa- 
ratus, provision was made for attaching engraved rings to the 
type wheel shaft, showing at a glance the time. But these are 
not found essential, as they would but little facilitate the set- 
ting of the type, which is accomplished as follows: The min- 
ute type wheel, which is free to move in either direction, 15 
revolved to correspond to the correct minute; an impression 
my then be taken, and the machine started, when the clock 
indicates the same; the seconds being readily counted from the 
beats of the magnet regulating the fast moving train. The 
whole time for this adjustment need never exceed two minutes. 
observation of zone stars, the type may be set to give 
the integer-seconds of mean right ascension, so that the final 
reduction will always be a small quantity. 
_ The constant use of this mechanism on every day and observ- 
ing night, for more than four months, during which time more 
than ten-thousand records have been made, enables us to speak 
with confidence of its success, both as regards correctness i 
printing and in saving of labor. 
_ Other things being equal, it is found, that for three observers 
twice as many observations can be reduced in the same time, a8 
when a recording chronograph is employed. 
