MacDougall specifically chose people who were suffering from conditions that caused physical exhaustion, as he needed the patients to remain still when they died to measure them accurately. When the patients looked like they were close to death, their entire bed was placed on an industrial sized scale that was sensitive within two tenths of an ounce (5.6 grams).[1][2][3] On the belief that humans have souls and that animals do not, MacDougall later measured the changes in weight from fifteen dogs after death. MacDougall said he wished to use dogs that were sick or dying for his experiment, though was unable to find any.