26 EFFECTS OF TEAK TAR ON CORDAGE. 
The first column shows the strength of the rope when made ; and the se- 
cond after having been exposed to the heat of a stove from 85° to 100' Fahr. 
The following experiments, also made by Mr. Chapman, confirm those of 
Duhamel, respecting the diminution in the strength of cordage produced by 
tarring. The ropes were registered on the improved principle, and were 
made with the same yarn, and with 17 threads in each strand. 
Girt Comparative 
in inches Strength, 
Cwt. Cwt. 
1806. Oct. 2. White rope . 2-75 Broke with 75 100 
» Oct. 24. Tarred rope . 2-8 a 55 73'3 
1807. May 8. Samerope . 2:8 ay 41-4 55:2 
The following experiments were made with ropes made of the same yarns, 
and of nine in each strand. 
Girt Comparative 
in inches. Strength. 
Cwt. Cwt. 
White rope . : 17 Broke with 27°5 100 
Tar of whale oil . 1:85 - 225 83:7 
Tar and tallow . 1:8 3 175 63°6 
Tar unpurified . 17 Pi 15°95 57°7 
Whale oil and tallow have therefore an excellent effect, particularly the 
former. 
* * * * 
The following experiments were made by Mr. Chapman on the elasticity 
of ropes of different kinds, when strained with Jths of their breaking stress: 
Original Length 
Length. | when Strained. 
: ; Inches. Inches. 
Registered primary strands . . 24 242 to 25 
Registered shroud laid ropes. . 24 26 to 263 
Common made shroud laid rope . 24 273 to 28 
Registered cable laid rope ; . 24 27 to 27% 
The three kinds of rope last mentioned, stretched on an average 1 inch in 
24 with a fifth of their breaking stress, which is from 3 to 2lb. of the whole 
stretching of the registered shroud laid ropes, but only from 2ths to th of 
the stretching of the common made shroud ropes, ‘ ‘ 
In May, 1805, Sir Joseph Banks, being anxious to try teak tar for ropes, 
ie ee lg were Pies of the same yarns, one with teak tar, and the 
other with common tar. ey were then pla i 
ee die ek seen placed in the same storehouse, and 
Common tarred rope broke with 3848 pounds, 
That made with teak tar broke with 5980 
wie common tarred rope being only about two thirds the strength of the 
other. 
It is interesting to conclude with a notice of the efficacy of 
an Indian product. It will probably be found that the Indian 
