278 



SCIENCE. 



[Vol. XIII. No. 323 



right tibia and fibula, were exposed to view. The hair and scalp 

 were burnt off the forehead, exposing the bare and calcined skull. 

 The tissues of the face were represented by a greasy cinder, re- 

 taining the cast of the features, and the incinerated mustache still 

 gave the wonted military expression to the old soldier. The soft 

 tissues were almost entirely consumed. On my return from other 

 work, later on, I found that the whole had been removed. The 

 bearers told me that the whole body had collapsed when they had 

 tried to move it en masse. From the comfortable recumbent at- 

 titude of the body, it was evident that there had been no death- 

 struggle, and that, stupefied with all the whiskey within and the 

 smoke without, the man had expired without suffering, the body 

 burning away quietly all the time." 



The Suppression of Small-Pox. — An outbreak of small- 

 pox is reported to have occurred recently in Minneapolis, and the 

 health-officer of that city is credited with having summarily and 

 successfully dealt with it. According to The Journal of the 

 American Medical Association, as soon as a case was announced, 

 a consultation was called to determine if the disease was small-pox. 

 That being settled, the patient was removed to the quarantine 

 hospital for treatment. The house where he lived was quarantined, 

 and all the people directly exposed were confined in it. Dr. I<Cil- 

 vington's assistants then began to look up all people indirectly ex- 

 posed, and vaccinated them. Quarantine houses had guards 

 stationed about them, who allowed no one to go in or out during 

 the season of quarantine. The quarantine people were vaccinated, 

 and during the time until it could be determined whether the vac- 

 cination would take, they were siipplied with food. When the 

 vaccination took, the person under quarantine was bathed, given 

 new clothing in the place of the old, which was burned, and he 

 was then discharged. When a house had been emptied of people 

 under quarantine, the bedding and curtains were burned, sulphur 

 burned in all the rooms, and the walls sprayed with corrosive sub- 

 limate. None of the inspectors or guards were allowed to enter 

 any of the houses under quarantine, when there was danger; and 

 the doctors that did the vacci?iatina- saturated their clothing with 

 the corrosive stiblimate before and after entering a house where 

 there had been small-pox. The clothing and bedding were either 

 paid for at a reasonable price by the board of health, or were re- 

 placed by new articles. In one of the houses quarantined, there 

 were 31 laboring men who were ijiclined to object to the rules of 

 quarantine. One escaped, but he was taken back when found, 

 and agttard, with a rifle and instructions to shoot should he at- 

 tempt to escape, was put over him. Since Jan. 13, six thousand 

 people have been vaccinated, and the schools, public and private, 

 have been systematically visited, and unvaccinated children vac- 

 cinated. The absurdity of saturating the clothing of the vacci- 

 nators before and after entering each house where there had been 

 small-pox is self-evident. Nor do we believe that in this enligh- 

 tened age any guard would be instructed by a health-officer to shoot 

 a laboring man who, after being shut up forcibly in a house where 

 a case of small-pox had been, should attempt to escape, especially 

 when the house had been disinfected, and the man himself vac- 

 cinated. The account above given must, we think, have been ob- 

 tained from some source outside the health-office of MinneapoUs. 



ELECTRICAL NEWS. 



Canal-Boat Propulsion. 



A PAPER read by Mr. H. C. Vogt at the last meeting of the 

 British Association for the Advancement of Science brought out 

 some interesting and remarkable facts. It gave the results of some 

 experiments made with air-propellers at Copenhagen. A steam- 

 launch was fitted with a windmill with steel blades, carried on a 

 frame above the deck, and provided with steam machinery to rotate 

 it. The London Electrical Review, in describing the experiment 

 and suggesting a modification of the method, says that at first sight 

 the method would seem an extremely inefficient one as regards ap- 

 plication of power to so unstable a medium as the air ; but when it 

 is remembered that recent investigations of the marine propeller 

 have established it as a true re-action engine, in which a large 

 slip is not necessarily an accompaniment of inefficiency, it will ap- 



pear that there is nothing wrong in the principle indicated by Mr. 

 Vogt. An air-propeller is a pure momentum or re-action machine. 

 Practically it was found that a twenty-foot launch of five and a 

 half feet beam could be driven at a speed of five knots per hour in 

 calm weather, and against a fresh breeze at four knots. The 

 engine producing this effect indicated one and one-half horse-power. 

 For a single indicated horse-power, the thrust of the propeller was 

 36.7 pounds, or about the same as a water-propeller. It might be 

 supposed that in a contrary wind this thrust would disappear; but, 

 on the contrary, through 75 per cent of the horizon the thrust was 

 found to be augmented by the wind. With a larger launch, hav- 

 ing a displacement of five tons, a speed of over six knots an hour 

 was obtained, against the wind. In some of the trials, canvas- 

 covered wings were used, but they were found inferior to steel. 



To replace the steam-engine used in these experiments, the Re- 

 view suggests an air-propeller carried well above the decks on a 

 standard, driven by an electric motor which is carried on top of the 

 frame, supplied with current from a wire running along the canal, 

 and connected with the motor through flexible conductors and a 

 carriage travelling on the main wire. The blades of the propeller 

 should be of steel, accurately shaped, and arranged to be turned at 

 a greater or less angle according to the direction of the wind. 

 Thus equipped, a canal-boat could make her way with a speed ex- 

 ceeding that generally used, and with no greater proportionate ex- 

 penditure of power than that existing in all cases where the trolley 

 system of actuating electric motors is in use. 



The advantages of the system are obvious. The hull of the 

 vessel would be entirely clear of machinery, and the entire weight 

 of the propelling apparatus carried by the boat need not exceed 

 that of an ordinary tow rope. No disturbance of the water of the 

 canal would be produced, except such as would be due to the pro- 

 gressive movement of the hull of the vessel. It would seem as 

 though in this suggestion might be found a solution of the me- 

 chanical driving of canal-boats, — one that, from the points of 

 view of simplicity, non-occupancy of the hull of the boat, and 

 minimum disturbance of the water, would be nearly perfect. 



The air-propeller works with an entire absence of vibration. It 

 requires ten or twelve times the area of the corresponding water- 

 screw. As the thrust is a perfectly quiet one, and, if due to the 

 motion derived from a dynamo, would be free from the jarring in- 

 separable from the motions of a heavy reciprocating engine, and 

 as it is cushioned in all its motions by the high elasticity and mo- 

 bility of the air, a very light frame would serve to carry the wheel. 

 A thrust of 75 to 150 pounds would be all that the frame would be 

 required to resist, — a thrust that would always be brought on it 

 gradually, and would be gradually released. In steam canal boats 

 a very considerable portion of the hull is occupied by the engine, 

 boilers, and coal-bunkers, while the constant eddies and currents 

 produced by the propeller are destructive in their effect on the 

 sides and bottom of the canal. This is all done away with in 

 aerial propulsion. The establishment of a line of poles and wire 

 would not represent the tithe of the cost of a fixed or traveUing 

 towing-cable. 



Influence of Light on Magnetism. — A prehminary notice 

 of a very interesting experiment has been given by Mr. Shelford 

 Bidwell. The investigation was undertaken to determine whether 

 a piece of iron could be magnetized by allowing a ray of light to 

 fall on it. Of course, if light is an electrical vibration, and if an ef- 

 fect was sought using an ordinary piece of iron, there would be no 

 result, since the opposite vibrations would exactly neutralize each 

 other's effects. But iron can be prepared so that it is more sus- 

 ceptible to a magnetic force acting in one direction than to one 

 acting in the other. Ewing has shown, that, if a piece of iron 

 which is being magnetized in what we call the positive direc- 

 tion has the magnetizing current reduced to zero at such a point 

 in the operation that the current and the magnetization of the iron 

 become zero at the same instant, then that piece of iron, although 

 apparently in a neutral condition, is more susceptible to a negative 

 than to a positive magnetizing force. So, if a piece of iron pre- 

 pared in this way be submitted to the action of a ray of light, the 

 positive and negative magnetizing forces produced, although equal, 

 will not balance with one another, but the latter should produce 

 an effect. On trying the experiment in this way, Mr. Bidwell ob- 



