462 



R O P E M A K I N G. 



Rope- before it comes in their rotation to pass through the 

 making, tar. When the full length of strand is made, the twist 

 ^ V ' of which is principally given by the revolution of the 

 frame, in which it is progressively wound up during 

 the process of making, the yarns are cut off; and three 

 of these strands, from so many stationary strand frames 

 (each of which has performed the operation last de- 

 scribed, revolving only round its own separate axis) 

 are concentred together, and pass through the axis of 

 one end of a rotatory frame, which twists them into a 

 rope and coils it up progressively as made, upon a bar- 

 rel within the frame." 



Mr. W. In the year 1 802, Mr. W. Chapman took out a pa- 



Chapman's tent "for the application of certain substances either 

 patent for separate or combined as a preservative for cordage." 

 preserving s it had been proved by Duhamel and others, 

 i-<m5ge, w h ose experiments we have detailed at the end of this 

 article, that cordage was injured by the operation of 

 tarring, it became a matter of great consequence to as- 

 certain the cause of this, and to obtain the advantages 

 acknowledged on all hands to belong to tarring, without 

 the evils which accompanied it. 



As tar was known to be soluble in water, attempts 

 had been made to defend cordage from the water by 

 oils and fatty bodies, which do not mix with it ; but 

 the application of these unguents was found to inter- 

 fere with the twisting of the fibres. Tanning has also 

 been used, but though it is found useful in the net 

 manufacture, it is not employed in cordage. 



Mr. Chapman, to whom the rope manufacture owes 

 so much, directed his attention to the subject, and 

 seems to have obtained very important results.' He had 

 found that rope yarn is considerably weakened by pass- 

 ing through the tar kettle ; that tarred cordage loses 

 its strength progressively in cold climates, and so ra- 

 pidly in hot climates that it is scarcely fit for use in 

 three years. 



Mr. Chapman, therefore, set himself to discover a 

 preserving substance with the following properties : 



1. That it should not be soluble in water. 



2. That it should not become rigid by length of 

 time, as the rope which imbibed it would be weakened 

 by sudden bendings. 



3. That it should be free of any acid or essential oil 

 capable of being disengaged by heat, for these ingre- 

 dients occasion the dry rot in cordage. 



Mr. Chapman found that tar could be rendered fit, 

 by the following process, for becoming a preservative 

 of cordage ; 



1. By boiling it in water, which will extract from it 

 its superabundant acid, and its mucilage, which con- 

 tains a disengaged acid. 



2. By repeating and combining these processes till 

 the tar has become more pitchy, by having thrown off 

 a larger portion of its essential oil, and by restoring the 

 plasticity which it has thus lost by the addition of suet, 

 tallow, animal oils, or expressed oils that may have the 

 same effect. 



3Ir Wil- The fo^owing report drawn up by our celebrated 

 liamAllen's countryman Mr. William Allen, on the advantages of 

 report on using Mr. W. Chapman's preparations of tar in cordage, 

 the effects of J s too valuable a document to be omitted here, 

 common tar f < Common tar, unprepared, contains a quantity of ve- 

 T ase> getable acid ; and, apprehending that this acid might 

 injure the texture of cordage, the following experiment 

 was made : A piece of twine, which, by previous trial, 

 was found capable of supporting 6l Ibs. without break- 

 ing, was immersed in vegetable acid, and after 46' 

 hours it was so much injured that it broke with a 



weight of less than 1 6 Ibs. A piece of the same twine Rope- 

 was immersed for 46 hours in the essential oil, which making. 

 came over in distillation from the jar ; and, although ** """" 

 it had suffered no diminution of strength at the termi- 

 nation of its immersion, yet after being exposed three 

 days to the air, it was only capable of bearing 31 

 pounds. 



The Stockholm tar used in these experiments was 

 found to contain about seven per cent, of vegetable 

 mucilage, capable of being converted into acid in a hot 

 climate, when the cordage is immersed in water ; the 

 tar also contained as much real acid as there is in an 

 equal measure of common vinegar ; but by repeatedly 

 boiling the tar in water, according to the method pre- 

 scribed, it is freed from its acid and mucilage, and 

 may be employed in the manufacture of cordage with 

 great advantage, in the place of common tar. Also, if 

 the prepared tar be boiled down so much further as to 

 deprive it of that portion of its essential oil which it is 

 found necessary to retain to prevent tarred cordage be- 

 ing too rigid, and the place of the essential oil be sup- 

 plied with a due portion of fixed or expressed oil, it is 

 probable that those injuries will be done away, which 

 arise from the action of essential oil on the fiores of the 

 hemp, and from the rigidity of cordage experienced in 

 vessels returning to cold from hot climates where the 

 essential oil is considerably thrown off." 



In I8l>2 the additional expence of using purified tar 

 amounted to about one pound sterling per ton, and the 

 experiments made on ropes tarred by this new method, 

 will be found at the end of this article. A vessel 

 was fitted out by Mr. Renwick of Newcastle, having 

 the cordage partly tarred in the common way, and 

 partly with purified tar, but she was unfortunately 

 lost on her first voyage. 



In I8C2 another patent was taken out by Messrs. Messrs. 

 James Mitchell, Sen. and Junior, for an improved me- Mitihell. 

 thod of manufacturing cables, hawsers, and other cord- Senior and 

 age. We have already seen that, in his patent of Ju n ' or ' s ! >a - 

 1799, Mr. Mitchell gave a slight twist to a small num- tellt ' lf 

 ber of yarns, which were combined into the strand as 

 if they were as many single yarns. The twist which 

 he gave to these sets or parcels of yarn was only 

 such as to shorten them between three and Jive fathoms 

 in every two hundred fathoms. The object of the pre- 

 sent patent is to facilitate the progress of combining 

 these parcels of yarn. After placing the sledge at a 

 proper distance from the head of the ropery, they at- 

 tach as many parcels of yarns as are wanted to as 

 many hooks on the tackle-board at the head of the 

 ropery, and run them down over the stake heads in 

 parallel lines. This is accomplished by what is called 

 a bedder, which admits and compresses each division se- 

 parately, and retires towards the sledge, the parcels of 

 yarn receiving their twist from the hooks on the tac- 

 kle-board. The strand is then made from those twist- 

 ed parcels of yarn in the ordinary way. After giving 

 an account of other analogous processes, the patentee 

 states, that the parcels of yarn may be twisted " with- 

 out rotation on the axes, by the simple process of 

 thorough putting the parts or subdivisions when 

 coiled above the boards," and drawing them on through 

 the proper distances, after they had been passed through 

 holes in the tackle-board. 



Mr. Huddart took out in 1805 a fourth patent for a ]\i r . HuiU 

 system of machinery, which, " though not new when dart'sfourth 

 taken separately, tends to lay cables in a manner patent, 

 that is to all essential and substantial purposes new." 

 This machine is composed of three strand frames, which 



