Rvfm whitley bay smoke cell rvfm wbsm this apparatus is used to demonstrate 39 brownian 39 or random motion of smoke particles a specially designed plastic box with a sliding lid contains a glass smoke cell a cylindrical 39 whitley bay 39 pattern condensing lens and a low voltage festoon bulb the components are pre adjusted so as to focus the light at the correct height in relation to the smoke cell ensuring that observation is enhanced rvfm whitley bay smoke cell