of the temperature, increased activity of the skin, fuller and slower respiration, gradually increased respiratory capacity, and diminished irritability of the mucous membrane in tubercular, bronchitic, or asthmatic patients.  There is also lessened discharge in those patients suffering from catarrhal conditions of the nasal passages.  In diseases of the respiratory system, a soothing effect upon the mucous membranes is always experienced, while cough and expectoration are diminished.

The cabinet used by Dr. Cleaves was large enough to contain a cot upon which the patient reclined.  An arc-lamp was suspended at each of the two ends of the cabinet and a flood of light was obtained directly and by reflection from the white inside surfaces of the cabinet.  By means of mirrors the light from the arcs could be concentrated upon any desired part of the patient.

Finsen, who in 1895 published his observations upon the stimulating action of light, is considered the pioneer in the use of so-called chemical rays in the treatment of disease.  He had a circular room about thirty-seven feet in diameter, in which two powerful 100-ampere arc-lamps about six feet from the floor were suspended from the ceiling.  Low partitions extended radially from the center, so that a number of patients could be treated simultaneously.  The temperature of the room was normal, so that the treatment was essentially by radiant energy and not by heat.  The chemical action upon the skin was said to be quite as strong as under sunlight.  The exposures varied from ten minutes to an hour.

Light-baths containing incandescent filament lamps are also used.  In some cases the lamp, sometimes having a blue bulb, is merely contained as a reflector and the light is applied locally as desired.  Light-cabinets are also used, but in these there is considerable effect due to heat.  The ultra-violet rays emitted by the small electric filament lamps used in these cabinets are of very low intensity and the bactericidal action of the light must be feeble.  The glass bulbs do not transmit the extreme ultra-violet rays responsible for the production of ozone, or the middle ultra-violet rays which are effective in destroying animal tissue.  The cabinets contain from twenty to one hundred incandescent filament lamps of the ordinary sizes, from 25 to 60 watts.  In the days of the carbon filament lamp the 16-candle-power lamp was used.  Certainly the heating effect has advantages in some cases over other methods of heating.  The light-rays penetrate the tissue and are absorbed and transformed into heat.  Other methods involve conduction of heat from the hot air or other hot applications.  Of course, it is also contended that the light-rays are directly beneficial.

Light is also concentrated upon the body by means of lenses and mirrors.  For this purpose the sun, the arc, the quartz mercury-arc, and the incandescent lamp have been used.  Besides these, vacuum-tube discharges and sparks have been utilized as sources for radiant energy and “electrical” treatment.  Roentgen rays and radium have also figured in recent years in the treatment of disease.