66 QUEENSLAND AGRICULTURAL JOURNAL. [1 Jaw., 1909. 
Answers to Correspondents. 
MEASURING STACKS. 
Farmer, Yangan.—We have already given several methods of calculatin 
the quantity of hay or wheatin a stack. You will find full directions in the 
Journal, Vol. IV., p. 18, circular and oblong stacks ; Vol. VI ., page 516, circulay 
stacks; Vol. VII., p. 285, circular stacks; and also in this issue, oblong stack, 
HOW TO MAKE A SUNDIAL. 
Srupent, Rosewood, wants to know how to make a sundial. 
Answer.—Why not buy a good clock? A sundial is of no use unlegg 
there is always sun to cast a shadow. However, as all sclentifig 
knowledge is of value, and to encourage other students, we give the 
following from the English Mechanic and World of Science :— 
Draw E F and AC for 6 and 12 o’clock lines, make angle C Ag 
equal to latitude of place, say 573 degrees. Draw D B at right 
angles to AS, cutting A Cin B. Lay distance D B from B to (0), 
make A Eand A F equalto AC. Join E C and F C. Through 
B draw 3 B9 parallel with EF. With centre C draw quadrant 
D B 2, and divide it into six. With centre C through these points, 
draw C1, C 2, Cll, C 10. With E and F as centres, draw 
segments M L and ON, and divide each into three equal parts, 
Through 3 and 9 draw 3 ITand 9 K parallel with AB. From E and 
F through T U and V W draw E5, E 4, and F7, F8. Lastly, 
from A draw lines to 1, 2, 3, 4, 5, 7,8, 9, 10, 11, and these will be 
the hour lines required. 
N.B.—The latitude of Rosewood is about 27 degrees 85 minutes south. 
The angle which the shadow edge of the stile should make with 
the plane of the dial should be equal to the latitude at the place, | 
and it should be in the plane of the true meridian, so that the edge 
is parallel to the earth’s axis; this requires that the dial be level 
sal the sides of the stile at right angles to the plane of the dial. 
Owing to the sun having a dise of considerable area, the shadow of the 
stile is not sharply detined, and there is a tendency to read time by 
the dial fast in the forenoon and slow in the afternoon. For 
correcting the clock time, therefore, a mean should be taken of a 
forenoon and afternoon observation if an observation cannot be 
taken at 12. Write to some mathematical instrument maker, and 
he will supply you with a dialling scale, which saves a great deal 
of time and trouble, and is cheap. 
