^^ 



The True Mora of British Guiana 



There are several tropical American woods comnionly knowu as 

 mora, but the one to which attention will be called here is the ma- 

 jestic mora of British Guiana. Botanists call it Dimorphandra mora 

 (Benth) and place it within the same group of plants as our black 

 locust. The mora has been called most appropriately the king of the 

 forest, as it forms a gigantic timber tree often growing to the 

 height of from one hundred and thirty to one hundred and fifty feet 

 and attains a trunk diameter of from eight to ten feet. It sometimes 

 reaches a height of nearly two hundred feet, but when it is as large 

 as this the tree generally has a hollow trunk at the base. The trunks 

 are branchless frequently nearly to the top; logs three to four feet 

 square and nearly one hundred feet long are obtainable exclusive 

 of sap-wood. Chief among the trees which in height and circum- 

 ference vie with mora are the greenheart {Nectandra rodite — Schomb) 

 and the West Indian locust (Hymemea courbaril — Linn). The latter 

 is a tree which grows to an enormous size, frequently attaining a 

 height of from sixty to eighty feet to the first branches and with a 

 diameter of from eight to ten feet. 



The mora is remarkable not only for its height, but also for its 

 tabular buttresses which are of an enormous size. In this respect 

 the tree resembles the common silk-cotton tree or ceiba (Eriodendron 

 anfraciuomm — D. C), of the West Indies. These buttresses or ex- 

 crescences are sometimes so completely decayed in very old and over- 

 matured trees as to represent wooden caverns upward of sixteen feet 

 high and sufficiently large in other dimensions to house fifteen per- 

 sons without exposing them to the influences of the weather. Although 

 the mora is interesting at all periods of the year, it presents the most 

 pleasing appearance during the time it is in fiower; the beautiful 

 dark green leaves contrast very strikingly with the snowy Avhite blos- 

 soms. It would be impossible to pass the tree in the forest without 

 admiration, even if it had no other qualification to recommend itself. 

 The trunk is usually very rugged and clothed with epiphytes, charac- 

 ters quite common in the tropical forests. The bark is about a quar- 

 ter of an inch thick, very even and uniform throughout, of a dull- 

 brown color, with occasional patches of white epidermis. 



The mora is found growing gregariously in rather swampy ground 

 in British Guiana and in the islands of Trinidad. It is one of the 

 few trees of the tropical forests which grow together in large masses 

 almost to the exclusion of every other kind. The mora is said to at- 

 tain its best development and to grow more abundantly along the 

 Barima river than in any other part of British Guiana. It is also 

 abundant in several other localities, particularly along the Moraballi 

 creek, Essequebo river, the Issoorooroo creek and upper Pomeroon 

 river. There are three varieties of mora, known as the red mora, 

 white mora and the morabucquia. The first two grow in swamps 

 and near the rivers and creeks. Both are very durable woods and 

 are probably of the same species. Morabucquia on the contrary 

 grows in high situations in clayey, rocky soil, and is not a durable 

 wood. It is not likely that true mora will be confounded with mora- 

 bucquia, which is a somewhat similar wood, but in the forest the 

 latter can easily be distinguished by its red and leathery bark. 

 Morabucquia is an entirely different species and has not been de- 

 scribed botanieally. 



The wood is of a chestnut brown or red color, hard, heavy, tough, 

 strong, and generally straight in the grain, but occasionally has a 

 twist or waviness in the fiber, which imparts to the logs possessing 

 it a beautifully figured appearance, giving them much additional 

 value. It is a handsome wood, but is somewhat marred by long lines 

 of a whitish secretion contained in the rather large pores. As it 

 takes a good polish, it is sometimes utilized as a substitute for rose- 

 wood or for the darker grades of true mahogany in cabinet-making, 

 and is employed extensively for many purposes in the arts. It is ex- 

 ceedingly tough and close-grained, and is now being imported into 

 England and occasionally into this country in considerable quantities 

 for use in ship and boat building. The imports of this wood into Eng- 

 land from British Guiana are increasing considerably. One of the most 

 valuable properties is its nonliability to splinter, even rivaling oak 



—42— 



in this respect, being, in fact, one of the toughest woods known. Its 

 outstanding merits are remarkable durability, a particularly high 

 breaking strain, exceptional strength, an average specific gravity of 

 about .915 (about fifty-seven pounds per cubic foot), and a prac- 

 tically unlimited power of resisting the action of water. Mora con- 

 tains an oily or glutinous substance in its pores, which is probably 

 conducive to its durability. It is considered by the most competent 

 judges to be superior, in some properties, to oak and African teak 

 {Oldfieldia africana — B. & H.) and to vie in every respect with 

 Indian teak {Tectonia grandis). 



It splits fairly evenly, saws with considerable diflSculty, planes 

 very well and smoothly, but slowly. It is hard to turn, and will not 

 cut to a smooth surface. The chisel has to te held in a position so 

 that it scrapes instead of cuts in order to produce a smooth surface; 

 the wood will then turn to a quite smooth and shiny finish. It polishes 

 very well and without trouble, on account of the closeness of its grain. 

 It is so uncommonly close-grained that it scarcely gives room for a 

 nail when driven into it. A number of writers ascribe to this wood 

 unstinted praise and various reports commend it for its qualities, the 

 chief of which are resisting dry rot and not splintering when used iu 

 war vessels. 



Mora has won for itself, by its exceptionally fine qualities, special 

 distinction in many building circles, notably in the sphere of naval 

 and marine construction. It is used largely for various engineering 

 and constructional purposes in harbor works, railway trestles, buUd- 

 ing, etc. It has proved a most suitable wood for the manufacture of 

 railway carriages, wagon work and heavy construction generally. This 

 good, sound, serviceable wood is used also for inside joiner's work 

 and for fine types of furniture and cabinet work, especially when 

 figured. Its chief use in England has been for beams, keelsons, en- 

 gine-bearers, and planking in shipbuilding. A full grown tree will 

 furnish logs of from thirty to forty, or even fifty feet in length, and 

 from twelve to twenty-four inches square taken from the main stem : 

 while the other parts would cut into the most choice and valuable 

 pieces in request for naval architecture; such, for instance, as keels, 

 stcmposts, iloors, cribs, beams, knees, breasts, backs, etc. 



Material Used in Barge Construction 



Interesting oljscrvations btiscd on systematic iuvostigatious are sub- 

 mitted in the August issue of American Forestry by A. E. Hageboeck, 

 in charge of the creosoting operations at the United States engineer's 

 otEce at Rock Island, 111. This office has been investigating for some 

 little time the durability of various kinds of wood used in the con- 

 struction of government and other barges for river work. The state- 

 ment of Mr. Hageboeck asserts that the decaying starts when there is 

 an excess of moisture together with air and heat and that in ninety 

 per cent of cases, deterioration begins in the ends of the timber. 

 In other words, the decaying progresses at the same rate as wood ab- 

 sorbs moisture through the ends. Inasmuch as a good pressure treat- 

 ment of creosote successfully plugs the ends of timbers, the article 

 avers that the good effect of this kind of treatment should be very 

 apparent. A rigid investigation of the changing conditions of barges 

 constructed of creosoted timber demonstrates that the additional 

 cost of this process is infinitesimal as compared to the saving in the 

 cost of repairs and the resulting increase in length of life. 



The article in question also treats of the inroads steel construction 

 has made in barge building, most notably in the construction of model- 

 shaped steamboat hulls. Creosoted timber in this type of construction 

 is not practicable because of the fact that a great deal of cutting is 

 necessary in framing, which results in exposed ends. While wliite 

 oak was formerly used almost exclusively in this foi'm of construc- 

 tion, steel is rapidly taking its jilace. Inasmuch as it has been found 

 practical to frame and then creosote timbers in transit for the con- 

 struction of scow-sliaped barges, it is likely that tlie use of such woods 

 as fir and pine will be continued for this purpose, as the cost is 

 very much less than steel. 



