brations as a remedy for neuralgia. The publication of M. Boudet de Paris was earliest in time; but Dr. Mortimer-Granville has been prosecuting researches on the subject for several years, while he intended to withhold the results from the public until the efficacy of the new remedy could be fully established. The publication of M. Boudet de Paris has, however, made it necessary for him to describe his own views and experiments, so far as he has gone, though he still considers them unperfected. His attention was drawn to the subject by the success of applications of ice in alleviating neuralgic pains in labor. Having persuaded himself that if the nerve affected in such pains could be strongly impressed, so as to change its state of irritation, the pain would cease, he tried the effect of tapping over the fifth nerve in ordinary facial neuralgia. The results were "very remarkable." He then devised an instrument, a percuteur, which would give a known number of blows in a second. The operations of this instrument were remarkable, although they are not yet considered decisive as to its efficacy. In numerous instances, pain was arrested by its application, and did not return. When applied over a healthy nerve, which was so situated as to be thrown readily into mechanical vibration, it produced a sensation like that caused by the passage of a weak, interrupted current of electricity, changing, when the action was prolonged, into a sensation of tingling, then of numbness, and finally to some twitching of the superficial muscles. A nervous headache, or migraine, could be produced by an application to the frontal ridges or the margins of the orbit. In some instances, when pain existed, the sensation was aggravated by the augmented state of vibration into which the nerve was thrown through the shaking of the adjacent tissues. It is noteworthy that a comparatively high number of vibrations per second seems to relieve a dull, aching, or grinding pain, while an acutely pitched and quick pain is most frequently arrested by a slower movement of the instrument. This is in harmony with the theory that the pain is the result of abnormal nervous vibration, and that the operation of the percuteur is to arrest those motions by opposing counter and interfering vibrations to them. M. Boudet de Paris relates in his paper that, by the aid of a large tuning-fork and sounding board, he caused hemianæsthesia to disappear; provoked contractions in hysterical patients at the Sâlpetrière as rapidly as with the magnet or electricity; and subdued the pains of an ataxic. With a modified apparatus he was able to produce local analgesia, often anæsthesia, in a healthy man, or a sensation of approaching vertigo, with a desire for sleep. An attack of migraine could be cut short by the application. Neuralgia, especially of the fifth nerve, disappeared after a few minutes' application of the instrument; but it was more difficult to get good results with the deeper-seated nerves. Both gentlemen suggest that the action of metallo-therapy, or of metallic applications, is best explained on the theory of vibrations.
Some Facts about Explosions.—Mr. Cornelius Walford has lately attempted to collate the statistics of explosions, as a help to ascertaining their causes and the means of avoiding them. A large increase in such disasters, which has been remarked in modern times, is easily accounted for when we remember that we deal with explosive materials and machinery vastly more than our ancestors did. The returns of the deaths from explosions in England and Wales, during twenty-two of the years between 1852 and 1879, give a total of 6,814, or 309 a year, of which 187 a year were ascribed to explosions of fire-damp, 37 to those of boilers, and 70 to those of chemicals, including gunpowder. Assuming, as the insurance companies do, that one hundred persons are hurt by such accidents where one is killed, a proportion which is not confirmed by the figures that follow, we have an annual average of 30,900 persons injured by explosions in England and Wales. No means exist of ascertaining the amount of property destroyed. Explosions of chemicals are increasing in frequency and variety of character as new processes are introduced in the arts. Remarkable instances of these occurred at Gateshead in 1854, when, during a fire, nitrate of soda and sulphur, neither of which would explode alone or in simple combinations, exploded terribly when water was brought to bear
