THE HAMILTON ASSOCIATION. 71 
DETERMINATION OF TIME AND THE TRANSIT 
INSTRUMENT (iLLustTRATED). 
Read before the Astronomical Section of the Hamilton 
Scientific Association, March 20, 1903. 
BYEvER eye BAKE Ob. Ss Dil. 1S. 
In presenting this paper before you to-night I do not in- 
tend to advance any new principle or theory but simply to tell 
in plain language to those members who have not studied or 
had the opportunity of seeing or handling the transit instru- 
ment the method and means by which we obtain time and put 
the transit instrument in adjustment for that purpose. Most 
of this paper may be found in any good standard work, such 
as Chauvenet’s Spherical and Practical Astronomy, or Loomis’ 
book on the same subject, and indeed the language and descrip- 
tion contained in those books can hardly be improved upon; 
therefore, I thought that a short description, with illustrations, 
might be of more interest than poring over the same subject 
in books without any one to enlighten you upon the difficulties 
that might be encountered. 
First of all, in regard to time, it is of indefinite duration, 
having no comprehensible begining or ending; in fact, you 
might say it is a species of motion with no beginning or ending, 
and to effect any measurement of a portion of this duration or 
motion we must choose some arbitrary unit. Any succession 
of events taking place at equal intervals of time, such as the 
oscillations of a pendulum, the flowing of a certain quantity of 
liquid from one vessel to another, the diurnal rotation of the 
earth on its axis or its annual revolution around the sun, would 
be convenient and useful methods of measuring portions f 
time. Of the latter two the daily revolution of the earth on 
its axis is at once the most accurate being uniform, and possess- 
ing practically that necessary qualification for a standard unit, 
namely invariability. 
