Description of a Self-acting Ventilator, #c. 143 



A, represents the front view of an air-tight vessel made with 

 thin copper, soldered at the joints with hard solder. Its 

 shape may be varied ; it may be made cylindrical, or other- 

 wise, so as to present a considerable surface to the sun's rays. 

 B, a tube communicating with the lower part of the vessel, 

 and with the small upright cylinder, C. D, a small rod of 

 brass, or copper, to the bottom of which is affixed a float or 

 buoy, of a size to move freely in the cylinder. E a small flat 

 iron bar, with a hole in the middle, to allow the buoy to rise 

 and fall. F, an adjusting screw, to regulate the opening of the 

 register. G, a rod to give motion to the register, by means of 

 small cranks, rods, or pulleys. No plan of the register is 

 given, because that must be adapted to the particular cir- 

 cumstances of the house, and its mechanism may be left to any 

 ingenious workman who understands hanging house bells. 



The vessel A, may contain from two gallons to ten quarts, 

 and must be painted outside with lamp black, mixed with a 

 size or oil, that will not leave a polished surface. When first 

 used the vessel must be heated sufficiently to expand the 

 internal air, water is then to be poured in at the top of the 

 cylinder, so as to give the required motion to the float, and 

 about half an inch of fine oil must be laid on the top of the 

 water to prevent evaporation. 



The register may be made to open at 75°, 80°, 100°, or any 

 degree required, by altering the adjusting screw. 



The vessel must be placed in front of the upper part 

 of the back wall, and at all times fully exposed to the light. 

 If the apparatus is of proper size, nicely constructed and 

 filled with a proper quantity of water, the registers, one 

 being placed in the upper part of the back wall, for the 



