THE VESSEL AS IT ArPEARS AFLOAT 



THE HYDROMOTOR SHIP. 



propelled by 



I 



We present a drawing of a vessel 

 hydraulic reaction, and recently 

 constructed at Kiel by Dr. Emil 

 Fleischer, of Dresden. 



Machines propelled on the reactive 

 principle are by no means a novelty, 

 but hitherto have been attended 

 with indifferent success. Nearly 40 

 years ago a model boat, which used 

 to travel up and down a tank pro- 

 pelled by such means, was exhibited 

 in London. But Dr. Fleischer's 

 hydromotor allows of as much as 90 

 per cent, of the indicated steam 

 power be'ng applied to the produc- 

 tion of the outflowing water stream, 

 while not more than 30 per cent, has 

 been secured with the reaction ma- 

 chines hitherto constructed. In his 

 vessel the usual ship's engines, 

 worked by means of wheel or screw, 

 are replaced by hydraulic reaction, 

 by the drawing in and shooting out 

 of a stream of water. The steam 

 power acts immediately on the 

 water, without any loss of such 

 power in conveyance from steam 

 engines and pumps. The manoeuv- 

 ring capabilities of the vessel are 

 greatly increased, and the usual 

 complicated machinery is replaced 

 by a remarkab'y simple contrivance. 



The professional men who took 

 part in a short trip with the hydro- 

 motor, expressed the most unquali- 

 fied appreciation of the invention, and of every detail ot its 

 execution. The easy manoeuvring of the vessel, its small 

 consumption of coal, and the practicability of adapting 

 the system to all rates of speed were clearly shown, and 

 the simplicity of its construction was regarded as partic- 

 ularly valuable for war ships. The hydromotor is under- 

 going further tests in English waters. 



HYDRODYNAMIC ANALOGIES TO ELECTRIC- 

 ITY AND MAGNET SM. 



From a scientific and purely theo 

 rttical point of view there is no ob 

 ject in the whole of the Electrica. 

 Exhibition at Paris of greater interest 

 than the remarkable collection of ap- 

 paratus exhibited by Dr. C. A. 

 Bjerknes, of Christiania, and in- 

 tended to shew the fundamental 

 phenomena of electricity and mag- 

 netism by the analogous ones of 

 hydrodynamics. I will try to give 

 a clear account of these experiments 

 and the apparatus employed ; but no 

 description can convey any idea of 

 the wonderful beauty of the actual 

 experiments, whilst the mechanism 

 itself is also of most exquisite con- 

 struction. Every result which is 

 thus shown by experiment had been 

 previously predicted by Prof. 

 Bjerknes as the result of his mathe- 

 matical investigations. 



It has long been known that if a 

 tuning-fork be struck and held near 

 to a light object like a balloon it 

 attracts it. This is an old experi- 

 ment, and the theory of it has been 

 worked out more than once. Among 

 others, Sir William Thomson gave 

 the theory in the Philosophical 

 Magazine in 1867. In general 

 words the explanation is that the air 

 in the neighborhood of the tun- 

 ing-fork is rarefied by the agitation 

 which it experiences. Consequently the pressure of the 

 air is greater as the distance from the tuning-fork in- 

 creases. Thus the pressure on the far side of the bal- 

 loon is greater than that on the near side, and the balloon 

 is attracted. 



Dr. Bjerknes has followed out the theoiy of . this ac- 

 tion until he has succeeded in illustrating most of the 



