_Habitual Motions and So-Called Rheumatism_.--The habitual movements of various trades are extremely important for the diagnosis of conditions that develop in the muscular system. Much of the so-called rheumatism of the working people is really due to the muscular over-activity demanded by their trades. This affects all kinds of working people. Men who have to work foot-lathes, or women who have to work sewing machines, or men or women who have to use their arms much in repeated vigorous movements, are likely to suffer from achy discomfort. The strong and healthy ones do not suffer, but the delicate do. The suffering is much more prevalent in rainy, damp weather; it is worse during the spring and fall than at other times. It is particularly noticeable whenever the patient is run down physically, is worrying about many things, or, above all, is getting insufficient nutrition. The discomfort is particularly likely to recur in those who do not know how to use their muscles properly, who are naturally awkward, and who perhaps have from nature an insufficient control over opposing and coodinating muscles, so that they do not accomplish movements quite as readily as would be the case if they were normal. The personal element enters largely into these affections. Many patients, however, can be trained to do their habitual movements under the best possible mechanical conditions, whereas very often they are found accomplishing them under the worst possible mechanical conditions. Men who have to do much writing may have to be taught the application of Gowers' rule, that the forearm should so move as a whole during writing that if a pen were fastened to the elbow it would execute exactly all the movements of a pen held in the hand. The writing must all be done from the shoulder. People who do typewriting may have to be instructed not to allow the machine to be too much above them, nor on the other hand, too much below them when they sit down. Young people particularly who, from long hours of practice on the piano, suffer from neurotic conditions, may have to be instructed to do this under good mechanical conditions. Men who do much filing of metal will often suffer from painful conditions in the arms. These will be much worse in case the filing is done at a table or workbench so high that pressure has to be brought to bear upon the file by the arms instead of through the weight of the body. This same thing is true for women who iron much. If the ironing board is so high that the additional pressure applied is made by the arms, then painful conditions will {175} almost inevitably develop if the work is long continued. These details are discussed in the chapters on joint and muscular affections.