JOHNSON, Rebecca, née Veneman. American poultry farmer, 1853-1921. After studying the way hens brood over eggs she concluded they periodically turned the eggs. So Rebecca made a warm incubator, incorporating egg turning devices. It was also necessary to invent a thermostat (bimetallic strip) accurate to within 1 degree of the optimum for hatching. The alarm went off if a drop in temperature of more than 1 degree occurred (an incubator alarm).