side up; in fact, as a rule, a downward vertical or nearly vertical position is usually the best for any blowpipe. As an example of this class of work, I may instance the shrinking on of collars and tires, which, with suitable ring-burner and a Root's blower, could be equally heated in five minutes for shrinking on; in fact, the work could be done in less time than it would usually take to find a laborer to light a fire. When the rings vary much in size, the burners can easily be made in segments of circles. But then they are not nearly so handy, as each needs to be connected up to the gas and air supply; and it is, in practice, usually cheaper to have separate ring burners of different sizes. Of course, you will understand that a ½-inch gas-pipe will not supply heat enough to make a locomotive tire red hot, and that for large work a large gas supply is necessary. Our own rule for burners of this class is that the holes in the tube should be 1/8 to 1/10 inch in diameter, from ¼ to ½ inch pitch; and the area of the tube must be equal to the combined area of the holes. The gas supply-pipe must not be less than half the area of the burner-tube. Those of you who wish to study this matter further will, I think, find sufficient information in my paper on "The Construction of High-Power Burners for Heating by Gas," printed in the Transactions of the Gas Institute for 1883, and in the papers on the "Use and Construction of the Blowpipe" and "The Use of Gas as a Workshop Tool." [Illustration]