1 72 Simple Way for determining the Time of Noon. 



Fig. 4. represents the back of the quadrant ; MM are the 

 screws by which the upper and lower limbs are fastened 

 after taking an observation. 



O, a spirit-level ; H, the tightening-screw for the joint 

 before noticed ; P, the socket attached by its joint and tight- 

 ening-screw to the back of the quadrant j the staff K is 

 screwed into the above socket. 



Fig. 5. shows the practical method of using the instru- 

 ment for determining the distances of the objects O and R 

 from the two stations S and T, at which the instrument is 

 to be successively placed, and used as before described. 



Fig. 6. is the diagram referred to at page 16*. 



Fig. 7. represents the mode of applying the tightening- 

 screw H, in fig. 1 and 4, by means of the semi-circular 

 spring, inclosing the cylindrical stem, or neck of the joint. 



XXVII. A simple Way for determining the exact Time of 

 Noon ; also a Way to obtain a Meridian Line on a small 

 Scale. By E?. Walker, Esq. 



To Mr. Tillock. 



SIR, Lynn, July 12, 1806. 



Although the following method of finding the exact time 

 of noon has not the merit of much originality to recommend 

 it, yet it may, I trust, prove acceptable to the young stu- 

 dent in astronomy, who may not have the means of pro- 

 curing expensive optica! instruments for solving this funda- 

 mental problem. 



Near the top of a room facing the south fix a plate of 

 metal with a circular hole in it, for the sun to shine through 

 from eight or nine o'clock in the morning until three or four 

 in the afternoon; then, by means of a line and plummet, 

 determine the point upon the floor which is directly under 

 the centre of the hole, and from that point, as a centre, 

 draw several concentric semicircles. - Having made choice 

 of some clear day near the summer solstice, make the room 

 nearly dark, and about three or four hours before and after 

 noon mark the points where the northern as also the southern 



limb 



