machines or novelties, announces to the incubator 

 people that he has just perfected a regulator that 

 he will put on his incubator this season, and that 

 he would like to furnish it at a low cost to the 

 manufacturers of incubators. The mushroom 

 concerns that have a regulator which does not 

 work, and some of those that have none at all 

 (which is far better, because you know you have to 

 watch them) jump at it, and then whoop that they 

 have something that they have tested for years. 

 They seldom know a good thing when they see it, 

 but the bitter complaints of customers cause them 

 to cast about for something else, and they are 

 ready for the next fake that comes along. 



Manufacturers of thermostats for fire alarms 

 have failed to produce one for incubators. 



Air, water, alcohol, and most liquids are affected 

 by atmospheric pressure, etc., and are not reliable. 

 Alcohol is rarely used in thermometers now, except 

 where extremely low temperatures are to be taken, 

 when mercury fails to act. Zinc expands well, but 

 fails to contract ; it gradually grows longer and is 

 useless. Mercury, if not confined, will evaporate ; 

 even when confined it is affected by moisture, and 

 is not a perfect material for a thermostat. You 

 may say, "If moisture affects a mercury thermo- 

 stat, why will it not affect a mercury thermometer? " 

 It does ; but a comparatively small amount of 

 mercury is used in a thermometer. As a proof of 

 this assertion, look at the very best hygrometers, 

 which are made by using a wet and a dry bulb 

 thermometer. Notice the difference between the 

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