518 



MISCELLANEOUS GARDEN STRUCTURES. 



one-fourth part of the water which escapes 

 by a simple aperture of the same diameter. 

 The cohesion of the fluid particles is di- 

 minished by heat, which, when increased 

 100°, nearly doubles, in certain cases, the 

 discharge." 



The quantity of water discharged by 

 pipes of different diameters, and under 

 different heads of water, may be found by 

 multiplying the area of the pipe in inches 

 by the square root of the head of water, 

 or the vertical height in feet, and that 

 product by 1 1 17.25. The friction in small 

 pipes is proportionably greater than in 

 larger ones ; but this is not very gene- 

 rally regarded in practice. The quantities 

 of water discharged in a given time, from 

 different sized pipes, the head of water 

 being the same, are to each other nearly 

 as the area of the outlets. 



Liquid manure tanks are of such great 

 importance to all gardens that no one 

 should be without them ; and their situa- 

 tion, as well as that of all other tanks 

 or cisterns, should be sufficiently elevated, 

 that the water may flow from them 

 throughout all the garden by its own 

 gravity, in pipes laid for the purpose. By 

 this arrangement the expense of pumping 

 will be saved. The advantage of liquid 

 manure applied for irrigation has been 

 exemplified in a most complete manner in 

 the gardens of the Marquis of Tweeddale, 

 at Yester House. The tank from which the 

 supply is obtained is placed in the farm- 

 yard, somewhat elevated above the gar- 

 den. This tank contains 5000 gallons. 

 The liquid manure is from thence con- 

 veyed to the garden, a distance of 900 

 yards, in earthenware pipes. In the centre 

 of each quarter of the garden is placed a 

 tank capable of holding 500 gallons ; and 

 from these, during the last year, no less 

 than 32,000 gallons have been used, with 

 the most marked effects. We should also 

 mention that liquid manure tanks are 

 attached to the hothouses, and heated by 

 hot- water pipes running through them, so 

 as to be at all times ready for use. The 

 crops produced by Mr Shearer give evi- 

 dent proofs of the utility of applying this 

 " nectar of vegetation." As regards the 

 construction of such tanks, we may, so far 

 as strength goes, refer to Mallet's, already 

 noticed ; but as disagreeable effluvia are 

 apt to arise from those intended for liquid 

 manure, we would propose the following 



arrangements to obviate this result. The 

 drains or pipes which supply them should 

 be carried down through the side walls, 

 as shown in fig. 733, 

 Flg ' ' " U so that the lower end 

 may be constantly 

 under the surface of 

 the water, to prevent 

 what is called a back 

 draught — that is, 

 the air and gases 

 formed in the tank 

 rising up through 

 the drains, and escaping at the surface of 

 the ground, or wherever the feeding-pipes 

 may be taken from, — or the drains may 

 be furnished with traps, so constructed as 

 to remedy this evil, as well as to prevent 

 sand and litter getting in. Of such traps 

 there is a great variety ; and many dif- 

 ferent kinds are to be procured from every 

 ironmonger. The best, perhaps, is that 

 of Cottam and Hallen, of London, of 

 which fig. 734 is a perspective view, and 



Fig. 734. 



735 a section. In the latter, a is the level 

 of the water, b the opening by which it 

 „ „ escapes, and 



F «' 735 - c the space 



where the 

 sand or other 

 sediment is 

 deposited. 

 When this 

 is to be re- 

 moved the 

 grating is 

 lifted off. In 

 the construction of such tanks it is 

 important that they be water-tight ; 

 this is effected by carrying up the walls 

 in 9-inch brickwork, set in cement, taking 

 care that the bottom and sides are well 

 puddled as the operation progresses. 

 Whatever their form be, the roof should 

 be that of a dome, if they are constructed 



