60 
Table VI. — Adhesion of Spikes in Ties— Continued. 
[Dry Hemlock tie, cut in winter of 1886 ; spikes driven seventy-five days previous to tests.] 
Tension in pounds on spike. 
Remarks. 
5. 50 
5. 50 
5. 00 
5. 50 
gin. 
Lag-screw 
|-in. 
Lag-screw 
4.90 3,110 
4. 75! 3, 390 
4. 25 
4. 55 
3. 20 
3. 25 
3, 690 
3, 280 
3, 580 
4,290 
2*000 
2, 060 
1, 800 
1, 850 
2, 580 
3, 600 
2,100 1,800 
1,900 1,700 
1,650 1,080 
1,60; 1,050 
1, 900| 910 
1, 280 900 
1,750 
1, 280 
820 
. 880 
520 
510 
1,300 
1,060 
420 
810 
280 
2i in. 
950 
880 
m 
540 
420 
Spike driven in g-inch hole ; 
yields suddenly and stops. 
Spike driven in j-inch hole ; 
yields suddenly and stops. 
Spike driven into solid 
wood. 
Spike driven into solid 
wood ; yields suddenly at 
start. 
f-inck hole bored ; size of 
screw, i-inch ; fibers of 
wood are sheared off. 
J -inch hole bored; size of 
screw, ^-incb; fibers of 
wood are sheared off. 
The table giving the adhesion of spikes shows some important 
features, a part of which will be new to the general railway public. 
In Chestnut of second-growth the tension necessary to start an ordi- 
nary T 9 g-inch square spike, inches loug, and driven home upon a rail, 
ranges from 3,000 to 3,600 pounds. After being drawn one-half an inch, 
the adhesion is diminished to only about two-thirds of these amounts, and 
at 1 inch is reduced to about one-half. This is of great importance when 
blocking up the track in winter, as a spike slightly redrawn will still 
hold. 
A spike redriven in an old hole holds about 50 per cent, of the amount 
that it will when first driven, unless the ties have been in service over 
three years. In the test of the second Chestnut tie it will be noticed 
that the adhesion of the spike has decreased with the length of the 
service. 
Experiment No. 8 shows that the adhesion of a spike driven into 
wood under the rails, after fermentation had taken place, is much de- 
creased, as might be expected.* 
In Yellow Pine the resinous matter forced out of the fibers by the com- 
pression produced in driving the spike lubricates the latter so that the 
adhesion is not as great as it should be according to the specific gravity 
of the wood; and after the spike is started the adhesion decreases rap- 
idly. This feature has been noticed when the rails are raised up on 
thick shims, the spikes holding but little in the ties, and being easily 
displaced. 
The fibers of the wood are broken and bent down, so that they do not 
close up tightly to the body of the spike, as in Chestnut and Oak ties. 
* Seo Figs. 1 and 2, p. 61. 
