108 ANNUAL OF SCIENTIFIC DISCOVERT. 



circuits for each stroke of the bell. A great economy of battery power 

 is thus obtained. In the place of the bells and striking machines, the 

 alarm circuit may be applied to setting off one or more air-whistles, at 

 such intervals as to give and repeat the district signal. The wires 

 may be insulated in a metallic tube and buried under the streets, 

 instead of the mode of suspension above the buildings. The system 

 proposed is a step in municipal organization, in advance of any here- 

 tofore attempted. It is an indication of a higher social development. 

 The municipal telegraph, in this and other applications, is to constitute 

 the nervous system of organized societies. A fire telegraph (probably 

 only for signalizing, not for mechanical agency, in connection with the 

 bells) is stated to be in operation in Berlin. A private signalizing 

 telegraph also connects the alarm-bell towers in New York. But these 

 are very distinct from the thorough organization which Dr. Channing 

 has proposed, and from the development of the motor functions of the 

 telegraph, described in the preceding pages. Editor. 



ELECTRO-MAGNETIC CLOCKS AT BERLIN. 



As there exist already at Berlin electro-telegraphic wires for signal- 

 izing fires, the same apparatus will also be used for the clocks. There 

 will be established several leading clocks in the different parts of the 

 town, which, being connected with the wires, wall indicate the time on 

 simple dials. The cost of such a clock and wires will be twenty-eight 

 thalers ; the subsequent yearly expense only four thalers. Such appa- 

 ratus can be applied at any private house, and an additional advantage 

 would be, that all these watches would keep an uniform and exact 

 time. 



EFFECT OF FUNNELS OF STEAMERS UPON THE COMPASS. 



THE following is a communication from Captain Johnson, E. N., to 

 Col. Sabine, containing the results of experiments made for the pur- 

 pose of determining the effect of the telescopic funnels of steamships 

 upon the compass : 



" I wish you to bring under notice the following results which I 

 obtained with reference to the effect of hollow iron cylinders upon the 

 compass, when placed inside each other ; the object being to ascertain 

 whether the whole difference of deviation, under the two conditions of 

 these telescopic funnels, was due to the difference of their elevation and 

 depression only, or whether a portion of the said differences was attrib- 

 utable to the induced magnetism of the separate parts of the funnel, 

 when lowered, acting upon each other. As it would have required 

 more time than could be afforded to hoist the parts of those huge fun- 

 nels in and out of the ship, while the requisite succession of observa- 

 tions were made, I procured three hollow iron cylinders of smaller 

 dimensions, their several diameters being such as to admit of one cyl- 

 inder being placed inside of another, and leaving a space of about one 

 eighth of an inch between their surfaces. Having placed a standard 

 compass on one of the pedestals in the observatory, and ascertained the 

 magnetic meridian for the moment by the collimator, the largest or 

 external iron cylinder (No. 1) was brought in and placed to the east- 



