196 



Current Meters, 



The types of current mtters, as shown in Figs. I, II, and III, in our former Catalogues, have been 

 omitted, owing to the many improvements made and embodied in the Meter, as shown in I- i^s. IV, V, and 

 VI, this Catalogue. We are, however, prepared to make to order Current Meter No. Ill, as designed by 

 Mr. Clemens Herschel, if so desired. 



Current Meter No. IV. 



The electric form of meter shown in Fig IV is especially adapted for observations 

 upon large rivers, arms of the sea, etc. It has its registering apparatus al><>ve tin- sur- 

 face of the water, or on the" bank of a river, and current measurements may be mail.* 

 with it at any depth, and may be continued for a week, or longer, without stopping, if 

 desired. Half a dozen or more of these meters maybe strung on one and the snme ver- 

 tical rod or wire, and simultaneous observations then taken of the velocities at different 

 depths below the surface. 



This form was used upon the gauging of the Connecticut River* by General Ellis, 

 and was designed particularly to avoid the catching of floating substances, such as 

 leaves and grass, upon either the vanes or the axis, and to render the record of tin; 

 instrument independent of the position of its axis with respect to the line of the current, 

 also, to get less friction upon the axis so as to measure low velocities accurately. 



This current meter is constructed upon the principle of Robinson's Anemometer, turning by the difference 

 of pressure upon opposite vanes of the wheel. The vanes of this meter, however, instead of being hemispher- 

 ical cups with a straight stem, are made conical at the ends, and are hollow and taper to the central hub, so as 

 to offer no obstruction to the slipping off of straws, leaves, or grass, as the wheel revolves. The central hub 

 is made tapering, so that any object can slide off easily, and it extends over the joints at the ends of t! 

 so as to enclose and protect them from floating substances. The axis runs in indium bearings. The forward 

 end of the frame which carries the wheel can be turned and secured in any position, so that the wheel can be 

 horizontal, vertical, or at any desired angle. 



The electrical connection is made by carrying an insulated wire from near the center of the instrument, 

 where the insulated wire from the battery is attached to it by a binding screw when in use, out to the end of 

 one arm of the wheel frame, whire it ends in a fine platinum wire resting upon a ring in the hub of the wheel. 

 This ring is made of alternate interchangeable sections of silver and hard rubber, secured in place by screws, 

 so that their position can be changed to register whole or part revolutions as desired. There is also a socket 

 and set-screw in the body of the frame near the center, for the return current, which can be carried through a 

 plain wire slightly twisted around the insulated wire so as to form one cord. If the instrument is run upon a 

 wire, or has a metallic connection with the surface, the return current can be made through that. A better 

 method now in vogue is to use a " twin " insulated wire. 



The universal motion at the center of the frame and the tail are of the usual construction. This meter 

 can be used in connection with any apparatus for registering the revolutions of the wheel by the breaks in the 

 electric circuit. 



Price complete, as in Pig IV, with electric register and one battery 

 etc., packed in three cases, ......... 



Price of this instrument without electric register and battery . . . 135.OO 



* For further information on this point, see Gen'l G. K. Warren's Report of Surveys and Examinations 

 of Connecticut River. 



We can have this meter, as well as Nos. V and VI, carefully rated at ait additional expense of from 

 $15.00 to $25.00. Unless ordered otherwise, the instruments will be sent unrated. 



Current Meter No. V, and No. VI. t 



An illustration of this instrument will be found on page 198. 



This form of Current Meter is specially adapted for observations upon smaller 

 rivers, streams, conduits, flumes, etc. It is provided with a registering apparatus. 

 For more extended observation upon rivers, etc., an electric register and battery similar 

 to those used with No. IV can be supplied with this instrument. The dial wheels 

 are completely protected by a glass cover, as shown by cut of meters V and V I. Tho 

 counting mechanism is operated by a string, by means of which the dial wheels are 

 thrown in and out of eear. One short pull on the string throws them in gear, and the 

 succeeding pull will throw them out again ; the next one in, and so on. 

 Price of Current Meter No. V, supplied only with the ordinary 

 registering apparatus, as shown in the main cut on pane 1 ( ,)8, and with 

 12 feet of brass tubing, made in sections of four feet, and graduated in 



feet and tenths. Complete In two cases, $1OO.OO 



Price of Current Meter Xo. VI, in all respects similar to that above, 

 but in addition to the ordinary registering apparatus this Instrument is 

 provided with an electric register, one battery and copper wir> 

 shown in the smaller cuts on page 198. Complete in four cases, . . 



{ For further information on this Current Meter, read " D.-scription of some experiments on the Flow 

 of Water, made during the Construction of Works for Conveying the Water of Sudbury Hi a," by 



A. Fteley and F. P. Stearns (Transactions of the Society of Civil Kirjn* i , I in M.m-i . 

 the Current Meter, together with a Reason why the Maximum Velocity of Water Flowing in open Channel! 

 is Below the Surface," by F. P. Stearns; a paper read at the Annual Convention of the Americ in Society erf 

 Civil Engineers, St. Paul, Minn., June 21, 1883. (Transactions, etc., Vol. XII., August, 1883). 



