The birefringence properties of the three mesogenic compounds 4'-n-propyl phenyl-4-(4'-n-pentyl cyclohexyl) benzoate (code name HP53) Trans-4-propyl cyclohexyl 4-(trans-4-pentyl Cyclohexyl) Benzoate (code name HH53) and 4-Pentyl cyclohexyl-4-(4-propyl cyclohexyl.) Benzoate (code name HD35) have been studied as a function of temperature. The variation of polarisibilities with temperature of the three mesogens has been calculated from birefringence studies and the orientational order parameter thereby determined as a function of temperature. Texture studies have been, conducted to confirm/identify the different mesophases of HP53 and HH53. The two smectic phases 1 and 2 of HD35 have been. identified as the smecticE and smecticB phase from texture and x-ray studies [1]. Comparison. has been made of values of the three mesogens. Also values of HD35 obtained from, the above study have been compared with values of the same obtained from x-ray methods [1].