PRACTICAL ARBORICULTURE 201 
1887, having grown in eighteen years. The tree was purchased to make a part 
of the catalpa exhibit, which was so admired. At the height of thirty feet it 
measured fourteen inches, and at the stump nineteen inches diameter. 
This tree would have made seven cross-ties, four from the first cut, two from 
the second, and one from the third cut. Numerous other trees could be shown 
giving equally good results. We note one other tree bought in Southern Indiana 
and shown in our exhibit. It was sixty feet to the first limb, at which point it was 
sixteen inches diameter, being twenty-eight inches thickness at the stump. It was 
forty years old. This tree would have made thirty-three standard cross-ties 7x8 
inches and 8% feet long. First cut, seven ties. Second cut, five ties. Third cut, 
four ties. Fourth cut, four ties. Fifth cut, four ties. Sixth cut, three ties. 
Seventh cut, two ties. From the top, four ties. 
It is needless to add that 1,210 trees of this size could not be produced on one 
acre of Pennsylvania soil, nor even 400 such trees. 
With 170 trees per acre, and averaging five ties per tree, one square mile will 
supply 544,000 sleepers in eighteen years, which, with tie-plates, will last one-third 
of a century. 
Seven square miles of good land will supply the Pennsylvania Railway east of 
Pittsburg with ties for one vear’s renewals, and seventy square miles will furnish 
timber for a complete renewal. 
After the first cutting the catalpa forest will produce a second crop in fifteen 
years, as the strong root system remains unimpaired after cutting down the trees 
and forces a rapid growth, producing the second forest crop fifteen vears before it 
is needed. 
By a system of yearly renewals covering ten years, the 620,000,000 sleepers 
in the railways of the United States can be replaced with catalpa from a forest 
covering less than six hundred square miles in one-third of a century from time of 
planting, the first crop being removed in eighteen years, and the second fifteen 
vears later. 
Thus one county of twenty townships would amply suffice. 
