| Answer | Crossword Clue |
|---|---|
| iriscope | an instrument showing colours of a prism |
| iriscopes | IRISCOPE, an instrument showing colours of a prism |
| sundials | An instrument showing the time by the shadow of a pointer cast by the sun onto a plate marked with the hours of the day |
| tachistoscope | an instrument for rapidly showing images on a screen to test perception |
| tachistoscopes | TACHISTOSCOPE, an instrument for rapidly showing images on a screen to test perception |
| cryophorus | an instrument for showing the decrease in the temperature of water by its evaporation |
| cryophoruses | CRYOPHORUS, an instrument for showing the decrease in the temperature of water by its evaporation |
