216 



SCIENCE^ 



[Vol. I., No. 8. 



The connection of the two carbons to the 

 prime mover of the clock is made by means of 

 a steel ribbon, F, attached to the lower ends 

 of the two rods g and I. This ribbon is led 

 over several pulleys, and is wound on a wheel 

 on the axis of the prime mover for a great 

 part of its circumference. The turning of this 



wheel is thus produced in a very certain man- 

 ner. The rod g slides in the tube D fastened 

 to the movable frame, and this tube is slit ver- 

 tically to allow the attachment of the ribbon 

 to pass. This manner of connecting the two 

 carbons, which replaces the chain used by 

 Serrin, and does away with the use of ratchet- 

 wheels, allows the carbons to be placed at any 

 desired height by a slight sliding of the ribbon. 

 Another peculiarity of this lamp is the mode 



of connecting the different interior parts of the 

 apparatus. The current of the large cable 

 arrives at the upper carbons bj' the rails and 

 uninsulated portions of the regulator. From 

 the lower carbon, it returns to the two insulated 

 terminals 11 and H', passing to one by the 

 movable frame, and to the other through the 

 electro-magnet S. The connections between 

 the contacts are made with four thick spu'als 

 of nickel-plated copper. Two are shown at 

 M and N. 



The tube D, which carries the rod g, is not 

 insulated from the frame ; but the latter is insu- 

 lated from the upright which supports it. This 

 is on account of ease of construction, it being 

 less difficult to insulate a straight piece than a 

 round tube like D. An air-pump, T, serves to 

 check the motions of the frame, and to prevent 

 too rapid oscillations. The porous plate V is 

 placed opposite the ends of the carbons, to 

 protect the rods t and I from the excessive heat 

 of the foyer. It is composed of the same 

 material as the porous vases used in batteries. 

 When the upper carbon rod arri\'es at the end 

 of its course, it acts on a bevelled piece, which 

 frees a contact spring, and suppresses the com- 

 munication with the line wire magnet, so that 

 it may not be injured by the passage of too 

 strong a current. 



THE WEATHER IN JANUARY, 1883. 



The monthly weather-review of the U. S. 

 signal service contains copious statistics of 

 the meteorological conditions, as observed at 

 171 regular stations in the United States and 

 Canada, 224 stations occupied b3' voluntary 

 observers, and 56 armj'-posts, besides various 

 other sources of information. The following 

 are given as the special features for the 

 month : — 



The very low mean temperatures. The de- 

 partures from the normal are most marked for 

 the upper lake-region, the upper Mississippi 

 and Missouri valleys. The average tempera- 

 ture for all the districts east of the Eockj' 

 Mountain range was 3.3° below the normal. 



The excessive rainfall over the south Atlan- 

 tic and east Gulf states, with a marked defi- 

 ciency in California. 



The heavy snow-storms in the west, block- 

 ading or impeding all railroad traffic. 



The chart on the opposite page has been 

 reproduced by permission of the chief signal- 

 officer from the regular chart No. III. of the 

 signal-service series. It contains lines of 

 equal air-pressure reduced to sea-level, lines 

 of equal temperature unreduced, and mean 



