vi Contents. 



January 28, 1884. page 



On the Microscopic Structure of a Boulder from the Cambridge Green- 

 sand found at Ashwell, Herts. By Professor Bonney ... 65 



On Critical or apparently Neutral Equilibrium. By J. Larmor . . 67 



On the small free normal vibrations of a thin homogeneous and iso- 

 tropic elastic shell, bounded by two confocal spheroids. By W. J. 

 Ibbertson 68 



On the curves of constant intensity of homogeneous polarized light 

 seen in a uniaxal crystal cut at right angles to the optic axis. By 

 C. Spurge 74 



Tables of the number of numbers not greater than a given number and 

 prime to it, and of the number and sum of the divisors of a number, 

 with the corresponding Inverse Tables, up to 3000. By J. W. L. 

 Glaisher 86 



February 11, 1884. 



On the Constitution of the Cell-wall and Middle Lamella. By W. 



Gardiner 87 



On the Head Kidney of Bdellostoma. By W. E. R. Weldon . . .107 

 On the early stages in the development of Balanoglossus Aurantiacus. 



By W. Bateson . 107 



February 25, 1884. 



On the sum of the divisors of a number. By J. W. L. Glaisher . . 108 

 On primitive roots of prime numbers and their residues. By A. R. 



Forsyth 120 



A comparison of Maxwell's equations of the electromagnetic field with 



those of Helmholtz and Lorentz. By R. T. Glazebrook . . .120 



March 10, 1884. 



Continuation of Observations on the state of an Eye affected with 



Astigmatism. By Sir G. B. Airy 132 



On the measurement of the electrical resistance between two neighbour- 

 ing points on a conductor. By Lord Rayleigh. (With an account 

 of experiments by R. W. Shackle and A. W. Ward) . . .133 



On dimensional equations and change of units. By W. N. Shaw . .137 



April 28, 1884. 



On the general equations of the electromagnetic field. By R. T. Glaze- 

 brook 142 



On the Pulsations of Spheres in an Elastic Medium. By A. H. Leahy . 153 



12, 1884. 

 On a Continuous Succession in part of the Guernsey Gneiss. By 



E. Hill 154 



