Crescograph : Instrument used to record the growth of plants.

Compass Needle : For knowing approximately the north-south direction of a place.

Cinematograph : Instrument used to reflect the image of picture on a screen.

Colorimeter : For comparing intensities of colour.

Cardiogram : Instrument used to trace .the movements of hearts.

Commutator : An instrument to change or reverse the direction of an electric current.

Dynamo: To convert mechanical energy to electrical energy.

Pyknometer : Used to measure the density and coefficient of expansions of liquids

Hydrophone : For recording sound beneath water.

Hydrometer : To calculate the specific gravity of liquids.

Galvanometer : For measuring currents of small magnitude

Eudiometer : It is a glass tube for measuring volume changes in chemical reactions between gases.

Electroscope : To detect the presence of electric charge.

Eco-Sounder : To measure the depth of sea.

Audiophone : Used to improve the imperfect sense of hearing.

Audiometer : An instrument used to measure the difference in hearing.

Anemometer : Used to measure the velocity and to find the direction of the wind.

Ammeter : This is used to measure the electrical current in amperes.

Altimeter : The instrument used in aircraft for measuring altitudes.

Accelerometer : An instrument that measures the rate of which the velocity of a body is changing.