May 3,1924 Relative Merits of Sweet Corn Varieties for Canning 415 
OOP 
likewise made use of this idea in the study of the resistance to puncture of the peri¬ 
carp of sweet corn as related to maturity and other factors, and reported an increase 
in the resistance of the pericarp to puncture with increasing maturity of the corn. 
In laying out the plans for the 
present investigations it seemed to the 
writers that inasmuch as the toughness 
of the kernel is of great importance in 
determining the quality of the canned 
product from sweet corn a wider 
application of the puncture test could 
be made to advantage and that a more 
convenient and practical instrument 
could be made than had hitherto been 
employed. A simple direct-reading 
puncturing apparatus was therefore 
devised, and tests were conducted upon 
the different varieties of corn at 5-day 
intervals throughout the critical period. 
A diagram showing the features of this //VP/B/9TOB- 
instrument is presented herewith. 
This apparatus consists of a glass 
tube 13 inches long, having an internal 
diameter of | inch and a plunger con¬ 
structed of aluminum rod ^ inch in 
diameter and 14 inches long, which is 
fitted with a small needle holder at the _ 
outer end, a thin square metal indicator BTBEL SPB/A/G 
at the other, and attached just below 
this indicator to a steel wire coil spring. 
This spring is made from No. 22 steel 
piano wire so coiled as to allow of exten¬ 
sion and contraction without coming 
into contact with either the inner walls- 
of the glass tube or the plunger passing 
through it at the center, and is attached 
on one end to the upper end of the 
plunger, as already described, and on 
the other at the lower end of the glass 
tube. The plunger is kept properly 
centered by means of the square metal 
indicator tip at the upper end, which 
moves sufficiently freely to make fric¬ 
tion insignificant, and.by a thin smooth 
metal guide at the bottom of the tube, 
which allows of free movement with BOB '3#6*x/4 
minimum friction. 4 The needle 
sists of a piece of No. 16 brass 
GBBDU&TED 
TO SMO/V 
GB/OM& OB 
PBBSSOBE 
con- 
wire. 
* Numerous trials were required to secure the 
proper length and extension of the spring. It was 
essential that the spring be so constructed and 
adjusted as to operate satisfactorily without fatigue 
within the effective*range of the tube, and to meet 
the needs as regarded the resistance of the kernels 
to puncture. It was likewise necessary that the 
spring be sufficiently sensitive to make the read¬ 
ings of resistance clear-cut and accurate. This 
condition was satisfactorily attained in the appa¬ 
ratus described. 
f/.£/A/&£/3 Of 
/-/OZ.£)f/S 
AKffOLfOf 7 
A/a /6B/Z9S SM£^ 
Fig. 3.—Diagram of instrument used in making 
puncture tests 
