VI. VELOCITY. 97 



1. Four hemispherical cups are fixed to the end of four strong metal arms 

 that radiate at right angles from a central boss, mounted on a horizontal axis 

 at right angles to a framework of metal, or other material, BO that they may 

 freely revolve when placed iu the water. The horizontal axis has fixed to 

 it a point or piece of platina ; upon this work pressing points or surfaces, 

 which can he made of any form, circular or otherwise ; each revolution of the 

 axis causes a contact to be made. 



2. The same receiving instrument, as used for the mining instrument, No. 

 .3388. 



3. A Leclanche battery, as used for the mining instrument. 



The receiving instrument can be placed in any convenient position on 

 board. 



N.B. No. 1. This part of the instrument is intended to be fixed at any 

 desirable and convenient part of the vessel, or it may be arranged to throw 

 overboard ; under such conditions it will give more accurate indications than 

 the logs now in use, for it is not affected like them in their motion by depth, 

 or the increasing density of water ; assuming that corrections be applied for 

 force and direction of currents, with respect to the course or line of motion, 

 the errors would probably not be found to exceed 5 per cent. 



402. Apparatus for indicating the Speed of a Ship by the 

 aid of Electricity. Be a net Woodcraft, F.R.S. 



4O9. Hhysimeter, without frictioual parts, for measuring 

 the speed of water or other liquids whether in pipes or open 

 channels. Alfred E. Fletcher, Liverpool. 



4O9a. Current Meter. 



Benjamin Thcophilus Moore, M.A. 



This instrument will measure the velocity of running water at any depth 

 below the surface, with accuracy and facility. 



The frame is formed of thin brass bars united in front to a solid ogival 

 head, and terminating, in the opposite direction, iu a double vane or tail. It 

 is suspended in water by a cord attached to a stirrup. 



The frame supports a hollow cylinder which is provided with six screw 

 blades, and is free to revolve upon fine pivots at its extremities. This cylinder 

 contains a water-tight glass tube within which is a simple train of mechanism 

 to record the number of revolutions made by the cylinder. This train of 

 mechanism is suspended in such a manner, that it remains at rest while the 

 cylinder revolves, and the dials which record the number of revolutions are 

 seen through the glass without opening the cylinder. When the instrument 

 is suspended iu running water by a cord attached to the stirrup, the frame 

 immediately takes up a position in which the axis of the revolving cylinder is 

 parallel to the direction of the stream. The cylinder is set in motion, and 

 stopped, at known instants, while under water, by means of a spring operated 

 upon by a light cord. 



For use in very deep water a simple automatic starting and stopping 

 apparatus is placed inside the water-tight compartment of the cylinder, which 

 operates in such a way that while the instrument is descending or ascending 

 in water, the mechanism does not record the revolutions of the cylinder, but 

 only while it is at the depth at which the velocity is required. In this case 

 the* spring is removed and one cord only is used. 



409b. Deep Sea Current Indicator. 



Benjamin Theophilus Moore, M.A. 



This instrument is intended to be used for the purpose of ascertaining the 

 direction of submarine currents. 



40075. G 



