cclx 



Theodore C. Link, Augustus Krieckhaus, and Oscar W. Collet 

 were elected to associate membership. 



Afril i6, 1877. 



Dr. Geo. Engelmann, Vice-President, in tlie chair. 



Fourteen members present. 



The Corresponding Secretary read a letter from Dr. L. de 

 Koninck, with acknowledgments for his election as Correspond- 

 ing Member. 



The Corresponding Secretary read by title a paper by Dr. G. 

 Seyffarth on " The Correction of the Present Theory of the 

 Moon's Motions, deduced from the Record of Classic Eclipses," 

 which was referred to the Publication Committee. 



Mr. Nipher exhibited an apparatus designed to give an alarm 

 in case of fire breaking out in a building, a bell being guaranteed 

 to strike as soon as there was heat enough to perceptibly raise the 

 temperature ; also an apparatus which would infallibly detect any 

 negligence on the part of a night watchman in making his rounds. 

 In his explanation he said : 



The best way to prevent the loss of life and property by fire is to prevent the 

 fire. There are two methods of discovering fires in their early stages : one 

 by the use of night watchmen, the other by the use of automatic heat-alarms. 

 Either of these means may be used alone, but it is better to combine them. 

 For controlling the movements of the night watchman many devices have 

 been put before the public. Without stopping to point out the particular 

 failings of any of them, I only need to say that the instrument should 

 fulfill these two conditions : it must be so constructed that it will not get out 

 of order; and, second, it must be so arranged that the watchman cannot 

 tamper with it without immediate and certain detection. This instrument 

 which we have here, invented and manufactured by Chas. Heissler, fulfills 

 both of these conditions in a very satisfactory way. It requires a battery 

 in the office, from which two wires lead to each station the watchman is to 

 visit, connecting them with a key. Connection is also made in the same 

 circuit with a recording instrument, kept in the office. The watchman 

 makes his rounds, changing all the keys, turning them all to the right and 

 then to the left in successive rounds. The changing of the keys reverses 

 the current in the recording instrument, where a little pencil at the 

 completion of each round marks a line on a time-dial showing when the 

 watchman finished his round. Should any one key be omitted, the cir- 

 cuit will be open and no record made. If the current is closed twice in 

 succession without the reversal of the keys, it is shown on the recording 

 instrument. 



