511 



GROUND TACKLE. 



GUAIACUM OFFICINALE. 



642 



3. Would not a tuddexly acting teat be preferable to a prolonged tension, 

 at present sustained often for upicardi of a quarter of an hour ? 



Fig. 7. 



4. Might not a chain after letting be annealed with advantage ? 



5. Are chains of present dimensions strong enough ? 



But the subject of ground-tackle has other important phases. 

 Question 5 suggests that there are times when a chain of sufficient 

 strength to meet an emergency would be far beyond all limits of 

 ordinary requirement, surpassing even the exigency figured above. 

 For many ships are lost on a lee shore, not so much from fairly riding 

 when at anchor, but from the ihackfelt in " bringing up " on first letting 

 go the anchor. Is it reasonable to suppose that a chain-cable manu- 

 factured with every possible care to bear a strain of (say) 95 tons, 

 could resist the violent and sudden shock of a mass like a line-of-battlu 

 ship of 120 guns, absolutely weighing above 4000 tons, and in a tlate 

 I 'erhaps driving at the rate of 6 or 7 miles an hour, or 

 upwards of 10 feet in a second ? 



We naturally, from this view of matters, turn to look in-board, in 

 order to scrutinise the means used in checking a cable under such cir- 

 cumstances, liut there are none positively none ! The cable is secured 

 by turns round solid blocks of wood of huge scantling, or iron, and 

 which are firmly attached to the framing of the ship itself. It may be 

 supposed that raring, or letting go more chain, is the remedy, but it 

 has its dangers also : for if once the chain resist the means of checking 

 its progress, it rushes with increasing force until, from the ship acquiring 

 velocity sternward, it is again suddenly checked by the clench of the 

 cable round the foot of the mast, and like packthread it parts, to the 

 most probable destruction of the ship. Another anchor may immedi- 

 ately be let go, but its chain too probably shares the same fate. 



Fig. 8. 



Stopper lanyard 

 for securing 

 chain. 



.A^k^^V 



The stopper is 

 shown as it ap- 

 pears while nip- 

 ping the chain. 



A simple remedy has been proposed, and is at least worthy of con- 

 sideration. If A and B (in Jig. 8) be two well-secured bitt-heads (they 

 need not be higher than 1 foot or 15 inches above the deck, as seen 

 at D)J the cable as brought in from the hawse-pipe passing round A, 

 and also round B with a contrary flexure, would, from the friction 

 exerted in letting go the anchor, be very much retarded. It is true 

 that an extraordinary strain might, in this case also, cause the cable to 

 ruth out with violence ; but if, in addition, there be inserted at c a 

 patent excentric stopper, such as is figured above (and which has been 

 in use for five yean in some of the largest ships), the moment the 

 officer of the deck might see fit he might cause to let go the lanyard, 

 X, of the stopper, and allow the friction of the chain along the face of 

 the purposely-lashed-open stopper ittclf to dote and nip the chain 



effectually, gradually or not as he might please. The nature of this 

 stopper admits of its being readily opened to veer away : indeed nothing 

 yet known is likely to be so efficacious. [WINDLASS.] The stopper 

 referred to is also peculiarly adapted for a position " chock-forward " 

 near the hawse-pipe, for one placed there would prevent the fatal 

 accidents which frequently happen from a capstan " running back " 

 while weighing an anchor, in consequence of a sudden strain coming 

 upon the cable. The stopper admits a chain or rope to pass through 

 it in the direction of the arrow, but if the chain slip back it is imme- 

 diately nipped by the exceutrie ; and with a great improvement on 

 every other method, inasmuch as it will be seen hi fg. 9 the curve rests 

 on three lints of the chain, all others rest on one ; and again in other 

 stoppers a rushing chain can never be restrained with certainty, for in 

 them, unless the link fall accurately into the " slot " prepared for it, it 

 runs on, and even a turn in the chain itself may cause this. 

 Fig. 9. 



(One side is removed to show the action upon the chain.) 



It is to Captain Thomas Brown, of the merchant navy, that we 

 owe great improvements, so far as they go; but until some such 

 additions as above suggested are made to existing means for working 

 ground-tackle, the gales upon our coasts will yearly diminish the profits 

 of the shipowner and underwriter, and hundreds of lives will be lost 

 in the most frightful of all calamities, the total shipwreck. 



GROWING CROPS. [EMBLEMENTS.] 



GROYNE, a timber estacade, or masonry bank, carried out from 

 the shore of a coast exposed to the action of a littoral current, for the 

 purpose of arresting, as far as possible, the onward progress of the 

 shingle transported by the current. If, indeed, the shingle were allowed 

 to advance without impediment, it would itself, by the abrasion it would 

 produce on the coast line, assist the encroachment of the sea ; but the 

 good effect of a series of groynes depends almost entirely upon their 

 being placed so closely to one another that no counter eddy can be 

 formed on the opposite side to the advance of the current. 



Groynes are largely used upon the chalk shores of the British 

 Channel, and upon the more yielding strata of the German Ocean. 



1 'KFKNCES.J 



GRUS, the Crane, a constellation of the southern kemisphciv, 

 introduced by Bayer. It is situated between Eridanus and Sagittarius, 

 a little below Piscis Australia. There are no stars of conspicuous 

 brightness in this constellation. 



GRUYERE. [CHEESE.] 



GUAIACENE. [GCAIACYL.] 



GUAIACIC ACID. [GUAIACTL.] 



OUAIACUM OFFICINA'LE, a tree, native of the West Indies, of 

 which the wood and resin only are used in Britain, but the bark also 

 on the continent, in medicine. The wood should be procured from 

 the duramen, or central part of the trunk, as being the richest in the 

 active principle. This wood should be very dense, heavier than water, 

 of an obscure greenish fawn colour : but the recent fracture is 

 yellowish, exhibiting an unequal cleavage, with a fatty shining appear- 

 ance, if the specimen be good. The wood of the circumference is 

 lighter, both in colour and weight, pale fawn, and opaque. In Guiana 

 the wood of the Dlpterix odorata (Tonka bean) is used under the name 

 of guaiac-wood, which it greatly resembles ; hence probably the state- 

 ment of some writers, that the guaiac-tree is a native of America. 



Genuine guaiac-wood is destitute of smell, but if rubbed, and still 

 more if set on fire, it evolves an agreeable aromatic odour. If long 

 chewed, the taste is peculiar, guttural, and bitterish. Trommsdorf 

 obtained from 100 parts 26 parts of resin of guaiac : one pound gives 

 two ounces of extract. The active principles are the resin and a 

 peculiar extractive. Guaiac-wood is used in the form of raspings (chiefly 

 obtained from the shops of turners who make blocks for ships of the 

 lignum vita;, as they term this wood) ; but this is a mixture of the wood 

 of the external and of the internal layers, of variable strength and 

 quality. The wood is less used than the resin. Guaiac-resin exudes 

 spontaneously, or in consequence of incisions, and hardens on the bark. 

 Resin obtained in this way is generally in spherical or long tear-shaped 

 pieces. It is also procured more abundantly by cutting the stem in 

 pieces of moderate length, boring a hole through it, then putting the 

 one end in the fire, and collecting the resin, which flows from the 

 opposite end, in calabashes. Another mode is to boil splints of the 

 wood in salt and water : also, by digesting the rasped wood and bark in 

 alcohol. 



There are some slight differences in colour, transparency, and other 

 points, according to the method of obtaining it ; but these ore of little 

 consequence, provided no accidental or fraudulent admixture of other 



