Synopsis Within the framework of limit equilibrium methods of stability analysis, no restriction need be placed at the outset upon the shape of the possible slip surface. In many cases, the critical surface may deviate significantly from a circle or a plane and therefore a method that facilitates the analysis of surfaces of arbitrary shape is of interest. A method for doing this is presented. The assumptions necessary to make the problem statically determinate are discussed. The solution of the governing equations ensures that all equilibrium and boundary conditions are satisfied. The method has been programmed for a digital computer and some examples of its application are given. Comparisons are also made with other methods of analysis. Dans la cadre des méthodes d'équilibre limite d'analyse de stabilité, il n'y a pas besoin d'imposer de restrictions au départ sur la forme de la surface de glissement éventuelle. Dans bien des cas, la surface critique peut dévier d'une manière significative d'un cercle ou d'un plan at par conséquent une méthode qui facilite l'analyse des surfaces de formes arbitraires présente un intérêt. On présente une méthode pour accomplir cela. On discute des hypothèses nécessaires pour que le problème soit déterminé au point de vue de la statique. La solution des équations dominantes garantit que toutes les conditions d'équilibre et de limite soient satisfaites. La méthode a été programmée pour une calculatrice digitale et on donne quelques examples de ses applications. D'autres méthodes d'analyse y son comparées.

No abstract

Synopsis Sysopsis The application of an electronic computer to stability analyses of earth dams with pore-water pressure is described. The analyses are based on Bishop's (1955)1adaptation of the Swedish method. The presentation of the data to the computer and its method of working are described and there is a brief discussion on the advantages of using the computer and possible future developments. On décrit l'emploi d'une calculatrice électronique pour I'analyse de stabiliti: des barrages de terre á pression d'eau interstitielle.Les analyses sont fondées sur l'adaption Bishop de la m6thode suédoise. L'on décrit ensuite l'introduction des données dans la machineet les diverses operations, et I'on discute brievement des avantages que présente I'emploi de la calculatrice, et de ses developpements éventuels.

Two methods are described for calculating, with the aid of a digital computer, the successive formation constants of a complex system, using ligandnumber data. Weighted least-squares criteria were used in both methods for determining the constants.A LARGE number of graphical methods have been described for calculating successive formation constants defining complex equilibria.l These methods tend to be subjective in nature and thus do not give objective estimates of the precision of the calculated constants; moreover, they weight the data in an arbitrary fashion, and are also often tedious to apply. More recently, several reports describe the use of digital computers for computing the constants, where by objective methods tests can be applied, but few (cf. ref.3) give detailed account of the methods for specific problems. The present Paper describes two methods which can be generally applied to one of the most frequently used experimental techniques for determining stability constants, vix. , the measurement of the pH of solutions of the ligands with and without the addition of the central co-ordinating ion. The methods of calculation apply specifically to mononuclear systems with a maximum co-ordination number of 2, but they can be easily extended to systems with a maximum of 3 or 4, and possibly up to 6, although a different numerical technique in which orthogonal polynomials are used would be more suitable for the problems of high order.4 EXPERIMENTALThe present work arose from a study of complex-formation between silver ions and a number of aliphatic amino-compounds. Full experimental details and complete results will be published later, but, briefly, the experimental technique is a refined form of the pH-titration method used by Bjerrum5 to give free-ligand concentrations [A] and the corresponding ligand number 6, at constant ionic strength of 0 . 5 ~. A newly developed cell with free diffusion liquid junction,$ in conjunction with a stable electrometer (E.I.L. Vibron), were used, so that e.m.f. measurements were reproducible to f O . 1 mv. WEIGHTING PROCEDUREThe system studied involved the following equilibria : andwhere A is an aliphatic amino-compound, it being understood that all species are solvated.Conventionally, two equilibrium constants are used to describe this system, viz. , p1 and p2, where PI refers to the first equilibrium, and P2 = @,, where k , refers to the second equilibrium. The formation function for such a system is given byThere will, therefore, exist a series of equations of the form where i i and [A]: are members of a set of experimentally determined values, and Ri, which should theoretically be zero, are residuals due to experimental errors. The problem was to Rossotti and Rossotti, " The Determination of Stability Constants, " McGraw-Hill, New York, 1961.

The variational co-detor method has been applied to calculate wave functions and energies for the P 2 and S 2 states of Cl, the S 1 state of Cl , the P 3 , D 1 , S 1 and P 3 0 states of S and the P 2 state of S. This is the first application of the method to atoms of the second chemical period, and is thus an application to considerably more complicated circumstances than have been previously examined. Except for the wave functions of the P 2 state of Cl and the S 1 state of Cl there are no records of any previous approximations of comparable accuracy to these wave functions, and no comparable predictions for any of the energy values. The introduction of relativistic corrections has been investigated and incorporated in this calculation. It was also found possible to adapt several sections of the calculation to the automatic calculating machine, the EDSAC, which has performed a considerable amount of the computation.