Air Holders.
Different lead burners have different views on this subject. Some prefer the bellows, with a contained air holder; some the air holder built like a gasometer, while others use an air holder similar to the generator in construction. These all have their advantages. For my part, I own and use all three.
The advantage of the bellows is that it can be easily transported and does the work perfectly, but it requires constant pumping, which soon tires the helper, and for that reason could not be used on jobs requiring more than four or five hours' labor.
The gasometer style of air holder is the easiest to use, if one does not employ a helper and has a large amount of work to do. The pressure can be regulated to suit the work by placing one or more weights upon it until the desired pressure is obtained. It does not require pumping up more than three or four times a day, which is its principal virtue. It is a perfect shop apparatus. Its disadvantage is that it requires a large quantity of water to fill it, which is not always available, and when full it is so heavy that it requires a truck to move it around.
By far the best air holder is the one shown as part of the apparatus in Fig. 9, and illustrated separately in Fig. 10. This only requires a few pails of water to fill it, and the exact pressure of the gas can be had by building it the same hight as the hydrogen gas generator. It does not require constant pumping, and I recommend this air holder for general use, as possessing more advantages, with less trouble, than any other air holder in use. However, all three will be described, and the beginner can make the one most suited to the material available.