140 BENJ. PIKE'S, JR., DESCRIPTIVE CATALOGUE. 



For the time in the forenoon, the shadow of that edge of 

 the gnomon next those hours, and parallel with the 6 o'clock 

 line, is that which is to be taken ; and for the afternoon, the 

 edge next its hours. 



Note. When the shadow comes to the meridian, or 12 

 o'clock, the whole thickness of the gnomon falls within that 

 space numbered XII. 



It is proper to know the variation of the compass at your 

 place, and the right allowance made. 



A little study with the instrument in the sunshine, will 

 clearly illustrate the foregoing directions. 



Price, $5.00 to $20.00. 



TJie Time Glass. An instrument serving to measure the 

 flux of time, by the descent or running of sand from one 

 glass vessel into another. Small ones running from two to 

 five minutes are frequently mounted in bronzed metallic 

 frames. (Fig. 142.) Price, 50c. and 63c. 



Fig. Ma 



Fig. 142. 



Larger time glasses (Fig. 143, as above,) are mounted in 

 frames of wood, either plain or highly polished, and may be 

 had running quarter, half, one hour, or two hours. Hour 

 glasses are used at sea for reckoning ; also, in academies 

 and schools where lessons are to be pursued for a given time. 

 Price, in plain frames, 1 hour, 88c. ; \ hour, $1.00; 



1 hour, $1.25 ; 2 hours, $1.75. 

 " in polished rosewood frames, 1 hour, 81.88 ; 

 hour, $2.00 ; hour, $2.25 ; 2 hours, $3. 



