Till-: MACADAM I A XI'T I\ I I A \\ \ [ I 1Q 
only 12 feet apart and- their branches as greatly interlocking except 
in a portion of the orchard where considerable pruning had been 
done in an experiment to give the interior of the trees air and light 
As a result of the investigation, Mr. Rumsey felt convinced that 
Macadamia trees should be set 30 feet apart when they are planted 
in orchard form. Rumsey (/6\ p. 34), quoting N. C. Hewitt, of 
Tweed Heads, gives a probable return of £250, equivalent to 
$1,216.65, per acre, starting from a conservative estimate of £25, 
equivalent to $121.65, per acre in the fourth year (seventh year in 
the south), and increasing to the fiftieth year' This would amount 
to about 5,000 pounds of nuts per acre, or an average of about 100 
pounds per tree from trees presumably set at the rate of 50 to the 
acre. A well-informed Macadamia grower in Hawaii, in making 
a conservative estimate as to yields, states that in favorable locali- 
ties the mature Macadamia tree averages 300 pounds of nuts annually, 
but that in windy localities, where the trees are not symmetrical in 
form and the blossoms have become more or less injured, the yields 
are smaller, possibly varying from 50 to 200 pounds per tree an- 
nually. The nut production of the average Macadamia is believed to 
compare favorably with that of the pecan, the walnut, and the 
almond. From observations made in Australia it is believed that the 
Macadamia will produce nuts for a period of 100 years. 
NUT CRACKERS 
Recently considerable investigation has been devoted to nut-crack- 
ing machines, both in Australia and in Hawaii. R. E. Carney, of 
California, has invented an electrical nut cracker which has a crack- 
ing capacity of 500 to 1,000 pounds of Macadamia nuts per hour. 
It is also reported (J, p. 228) that a St. Louis, Mo., manufacturer 
has a nut-cracking machine which is adapted to cracking almost any 
kind of nut. Given a trial with the Macadamia nut, sent to St. Louis 
from Hoaeae ranch, near Waipahu, Oahu, the machine is said to 
have worked very satisfactorily. The nuts passed through the 
cracker, permitting the kernels to fall unbroken from the shells. It 
is stated that the nuts do not require grading for this machine. It 
cracks them at the rate of 150 per minute. 
SPECIAL INVESTIGATIONS 
Rumsey (16), who recently made an investigation of the Macada- 
mia nut, particularly in Australia, visited a large portion of the 
country where it grows, both wild in the forest and in cultivation. 
He observed considerable variation in both the character of the trees 
and the nuts. He also interviewed the growers, some of whom were 
growing thin-shelled nuts and were hopeful of developing a market- 
able strain of that type. A standard variety of thin-shelled nut 
would prove to be desirable for table use and would offer advantages 
for cracking when sold on a commercial scale. The Wallongbar 
Experimental Farm in Australia has also succeeded in developing a 
comparatively thin-shelled nut by selective breeding, btit results of 
experiments indicate that as yet the variation in the seedling pro- 
duction is too great to maintain a standard variety. Any standard 
variety of thin-shelled nut must apparently be perpetuated by some 
