Processes in the Useful Arts. 345 



can DE ; which shuts sluice BC When these streams increase, so as to 

 produce as much water as two of the sluices (BC) can pass, then the ri- 

 vulet IK will have swollen so as to flow out at aperture 2, and thence 

 through P into a second can, which shuts a second sluice. When they 

 increase so as to produce a quantity equal to what three of the sluices 

 (BC) can pass, then the water in the rivulet IK will have risen so as to 

 flow out at aperture 3, and thence through R into a third can, which 

 shuts a third sluice. 



Again, suppose the weather to become fair, and the streams begin to 

 decrease, by the time they fall short, a quantity equal to what one sluice, 

 (BC) can pass, the water in the rivulet IK will have fallen so as not to 

 flow out at aperture 3, and, of course, one can will be empty, and one 

 sluice open ; by the time they fall short, a quantity equal to what two 

 sluices can pass, the water in the rivulet IK will have fallen so as not to 

 flow out at aperture 2, and a second can will have become empty, and a 

 second sluice open. When they shall have fallen short a quantity equal 

 to what three sluices can pass, the water in the rivulet IK will have fallen 

 so as not to flow out at aperture 1, and a third can will have become 

 empty, and a third sluice open, &c. &c. 



In this way the water may be regulated at pleasure ; and if a small re- 

 servoir were made near the works to retain the water that flows during 

 the night, (or when the mills are not at work,) not a drop would be lost * 

 The purpose, however, for which this apparatus was invented was dif- 

 ferent. Having occasion to cut an aqueduct round the bases of some hills, 

 to collect water and convey it to a reservoir at a considerable distance, I 

 found, that, to make the aqueduct large enough to convey a.l the water as 

 it fell during floods, would be very expensive ; it therefore occurred to 

 me, that, if a part of the water could be detained during floods, and 

 brought away gradually afterwards, a much smaller, (and, of course, 

 much less expensive,) aqueduct would answer the purpose. I therefore 

 made a small reservoir at a convenient place, and contrived these sluices 

 to shut during very heavy rains, and open again as they became lighter, 

 which answered the purpose completely, and was the origin of all these 

 weather sluices. 



3. On coarse Paint made with Potatoes. 



Take a pound of potatoes, skinned and well baked. Bruise them in 

 three or four pounds of boiling water, and then pass them through a hair 

 sieve. To this add two pounds of good chalk in fine powder, previously 

 mixed up with four pounds of water, and stir the whole together. This mix- 

 ture will form a sort of glue capable of receiving any kind of colour, even 



• The apparatus, "Vol. III. Plate I. Fig. 9, will accomplish the same thing with- 

 out this small reservoir ; but, in most cases, (particularly where the elevation of the 

 reservoir above, and its distance from, the works if great,) the expence would 

 be much greater than in this. 



