This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Two main purposes are fulfilled by heat acting as a stimulant; first, to elevate the depressed, or support the failing functions; and secondly, to equalize the distribution of the blood and nervous energy, by attracting them away from parts where they may exist in excess towards the seat of its own immediate action. These two indications not unfre-quently exist in the same case, and are fulfilled by the same application of the remedy; as in those instances of great prostration, with concentration of the blood in the interior, which are presented in the initial or cold stage of malignant fevers. Here the stimulant influence of heat, applied to the surface, rouses the prostrated nervous centres and the heart, while it calls forth the accumulated blood from within, and unloads the oppressed vital organs. Frequently also the two purposes are separately fulfilled; as when heat is applied, in one instance, to aid internal stimulants in supporting the sinking system in the advanced stage of febrile diseases, and, in another, to draw excitement away from the brain or lungs, towards the lower extremities in threatened apoplexy or pulmonary congestion. But it will be most convenient to treat of the special uses of the remedy, in connection with the several modes of applying it, which are next to be considered.