274 



CREAMERY BUTTER MAKING 



heat and smoke pass along the underside of the boiler 

 toward the rear and return through the fire tubes. To 

 prevent radiation of heat the brick work must be built 

 up to cover the entire boiler. The fire box must be con- 

 structed of the best fire brick. 



Fig. 76. -Glass 

 gauge. 



Fig. 77. -Gauge 

 cocks. 



The various boiler accessories will be described in the 

 following paragraphs. 



Glass Gauge. This is a glass tube attached to the 

 side of the boiler to indicate the height of the water in 

 it. The gauge is represented in Fig. 76. It is so attached 

 that its lowest point is about two inches above the highest 

 part of the fire line of the boiler, its entire length being 

 usually about fifteen inches. The cock at the bottom is 

 used to blow out the sediment that is liable to block the 

 opening between it and the boiler. When this occurs 

 the gauge becomes a false indicator. Frequent blowing 

 out is therefore necessary. The cock next to the blow 

 out admits the water from the boiler. The cock above 

 this admits the steam. When the glass breaks shut off 

 the water first, then the steam. Always have a few extra 

 glasses on hand so that the broken one can be immediately 

 replaced. Owing to its tendency to clog, the gauge can 



