274 SCIENCE LETTER FROM PARIS. 



turn a cock, and help himself to all the appliances of the fire brigade. It is in these 

 pillars that the water from the roof of the building is conveyed into the central 

 sewers. The air entering under the grand vestibule is cooled in its circulation 

 along the catacombs, out of which it escapes through the interstices of the floor- 

 ing, being sucked up by the vane arrangement of the roof; but as the latter is 

 lined with sheeting to blind out the sun, the ventilation of the Champ de Mars 

 leaves much to be desired. So far however, the rain has been more general than 

 sunshine. 



Another point deserving of notice, is the splendid span-work, in the roofing 

 of the vast machine galleries. Up to the present engineering has produced nothing 

 so bold, combining lightness, width and strength. The cold and severe lines of 

 the iron structure have been happily relieved by the adoption of the old plan of 

 ceramic decoration ; the fantastic coloring of the faiences produces a very agree- 

 able effect. 



The sea is agitated by three kinds of movements ; currents, ground swells, 

 and waves. The second consists of long undulations, which never break into 

 foam, and are produced by the impulsive action of winds blowing at a great dis- 

 tance and developing only an undulatory motion checked by a calm, or an 

 opposite wind. The swell is very inconvenient from the rolling effects it produces 

 on the ship — and unhappily, on the passengers. M. Bertin has resumed his 

 studies on waves — their height, length, and duration. Admiral d' Urville gave 

 the greatest altitude to waves; as much as 108 feet he estimates some off the 

 Azores in 1820; but Arago roundly asserted the measurement was inexact and 

 considered 26 feet the maximum elevation. M. Bertin agrees with Arago, while 

 averring that waves 39 feet high are infrequent, and those of 60 very rare. The 

 length of a wave may vary from 120 to 140 yards — M. Mottez says 450 yards — 

 and their duration from 23 to 28 seconds. Pending squalls in the Bay of Biscay, 

 by the aid of the oscillometer, M. Bertin determined that the duration of the roll- 

 ing of a vessel is constant for the same ship and for the same state of its cargo, no 

 matter what may be the intensity and the duration of the succession of the waves. 



Dr. Rizzoli, an Italian, relates a singular circumstance connected with an 

 infant, who fifteen days after its birth had a tumor on the small of the back, out 

 of which was growing a tuft of hair two inches long. By means of compression, 

 he reduced the tumor in the course of a year, but the tuft of hair, similar in color 

 to that on the head, continued to flourish. The girl is now seven years old, en- 

 joys perfect health, and the tuft of hair, color changed to chestnut, extends to her 

 knees. 



Dr. Couyba, of St. Seirade, has had under his care a cabinet maker who 

 suffers from the mania of a desire to kill somebody and the torture resulting from 

 his efforts to not commit murder. The patient is 21 years of age, and when seven 

 years old he was brought to witness an execution ; since then his malady. The 

 doctor compelled him to relate his history, and by prescriptions of phosphuret of 

 zinc has completely cured him. The same medicament has been employed by other 



