MECHANICS AND USEFUL AKTS. 61 



Haarlem Lake, has published a final report on the condition of the enterprise. 

 The total expense of the undertaking, from 1839 to 1855 inclusive, has been 

 8,981,344 florins; the revenue proceeding from the land redeemed and sold 

 is estimated at 8,000,000 florins. The land was at first valued at 200 florins 

 per hectare (2.471 English acres). Subsequent examination proved that the 

 soil laid bare by the draining operations was of far greater value than was 

 originally supposed. Thus in 1853, 784 hectares brought 575,000 florins, or 

 733 florins per hectare ; and though subsequent sales have not realized such 

 large prices, yet the land commanded a much higher price than the first valua- 

 tion. "This result," says M. D'Endegeest, " surpassed all expectation, inas- 

 much as the grand object of the drainage was rather to put an end to the 

 encroachments of the lake, than to make a lucrative speculation of it." It is 

 stated that a great number of farms are springing up on all sides, and that 

 the cultivation of the rich land is affording employment to many hundreds of 

 laborers. The total amount of land available for agriculture is estimated at 

 18,000 hectares ; and by proper care and supervision it is confidently expected 

 that no water overflows will take place.* 



BEARINGS FOE JOURNALS. 



Boxes composed of brass, or of brass lined with soft metal, have long been 

 used for supporting revolving shafts, but of late years iron boxes have been 

 considered by many nearly as good, if kept well oiled. The very latest 

 change seems to be a tendency to go back to the still more ancient practice of 

 employing hard wood as the material for this purpose. The British steamer 

 Himalaya, having had the old brass bearings removed, substituted lignum 

 vitse bearings to her screw shafting, which have operated much better. A 

 correspondent of the London Artisan thus describes the results of their 

 application : 



"Since the apph'cation of this material the vessel has run about 30.000 

 miles, during wliich time the engines have made about 8,000,000 revolutions. 

 The total wear down in the stern post does not exceed ^ inch, which is, of 

 course, very trifling for the work done. The screw shaft is lined with brass 

 at the part bearing on the wood, and this bearing is 18 inches diameter by 

 four feet long. The lignum vita? is inserted into the cast iron stern pipe in 

 segments, each piece being the whole length of the bearing, and about 3 

 inches wide by inch thick, so that the segments combine into the form of 

 the pipe, in a somewhat similar way to the staves of a cask. The abutting 

 edges of these segments are rounded off to form water-ways, and their sur- 

 faces are also scored in several places, to allow a free circulation of water on 

 every part of them. These segments are prevented from running round with 

 the shaft through its friction by a strip of metal, wliich is pinned on to the 

 upper side of the stern pipe, and against the edges of which the lignum vitas 

 segments abut. They are kept in at the inner end by a shoulder in the 

 stern pipe, and at the outer end by a ring, wliich is screwed on to the 

 stern post." 



* See Annual of Scientific Discovery, 1853, pp. 31-84. 



