154 LESSONS ON TIMBER-PRESERVING. [July 



area of 14,000 or 15,000 tenbos (1 tenbo = about 36 square feet), 

 and its owner keeps his office near by, so that he may transact his 

 business on tlie spot. 



The circumference of the pond is built of stone or wooden walls, 

 and a canal is dug on one side to communicate with the river and 

 thence with the sea ; the iiow of the tide being regulated by means 

 of a sluice. The pond should not be deeper than 5 feet in the 

 central parts at full tide, and not shallower than 2 feet in the 

 margin at ebb tide. The right proportion of salt and fresh Avater 

 for the pond is 6 parts of the former to 4 of the latter ; for if the 

 salt water exceeds this proportion, timber becomes blackish in 

 colour, and is liable to be much eaten by worms ; if, on the other 

 hand, the proportion of salt water becomes less, it is much sooner 

 decayed than otherwise. 



The velocity of the flow of tide should also be very carefully 

 regulated, for if the current is eitlier too rapid or too slow, timber 

 is again very liable to be much injured by worms. Hence, in those 

 places where there are two or three ponds near one another, their 

 owner generally amalgamates them, on agreement, by means of 

 small canals, which arrangement regulates the flow of tide very 

 considerably. Timber for storing is usually piled in five layers 

 according to its quality ; the lowest layer consisting of middle-class 

 timber ; the next layer of first-class timber, the next layer above 

 again of middle-class timber ; the next layer of third-class timber ; 

 whilst the uppermost layer, which is usually exposed above the 

 surface of the water, consists of very low quality, and by its weight 

 the lower four layers are kept sunk under water. Those five layers 

 are piled one upon another alternately at right angles, so that the 

 whole arrangement presents the appearance of a toothed cube. 

 Sometimes, however, the pile consists of only two or three layers ; 

 in that case they are tied to a big timber (about 12 to 15 feet in 

 length, and 7 or 8 inches in diameter) standing near by, and are 

 thus prevented from floating about freely ; sometimes also one or 

 two separate pieces of different kinds of timber are kept in the 

 pond for specimens. The durability of timber depends greatly on 

 the amount of care bestowed on it, and to this end the washing is 

 the most important. Twice in a year, generally in June or Novem- 

 ber, the cubical mass of timber above described is disengaged, 

 and each piece is well washed by means of a straw brush. The 

 different pieces are then reconstructed in a cube, but with the 

 following alteration in the arrangement: the middle-class timber 

 which before constituted the third layer, now forms the lowest 

 layer, and the middle-class timber which in the former case was 

 at the very bottom, now occupies the third layer. If washing 



