| name of the apparatus | Parabolic Metal mirrors with iron ball |
| classification | heat |
| name on the ledger | reflecting concave mirrors |
| purchased year | 1881 |
| demander | unknown |
| maker | unknown |
| seller | unknown |
| price | 4 yen |
| This is a set of apparatus, consisting of two parabolic brass mirrors, one iron ball with metal support, showing reflection of sound waves or thermal waves. In the experiment on sound, two mirrors are arranged as the concave surfaces are face to face each other. Place a watch at the focus of one mirror and a nozzle of a pipe at the focus of the other mirror. If you put your ear to another nozzle of the pipe, you are able to hear the sound of ticking the watch very clearly. The iron ball is used as a heat source in the experiment on heat. | |