732 REPORT—1896, 
structure as without boundaries, has corresponding to it an infinitude of other points 
whose situations in the structure are precisely similar, so that all of the infinite 
number of geometrical point-systems respectively obtained by taking all similarly 
situated points are regular infinite point-systems defined by Sohncke as systems of 
points such that the arrangement about any one of these points of the rest of the 
points of the system is the same as it is.about any other of them,’ ! 
This definition is not limited in its application to point-systems or assemblages 
of particles; it may be obeyed by any kind of structure, whether material or merely 
ceometrical, whether filling space or continuously ramifying through it, or distributed 
through it in discrete patehes. Itmay, too, be obeyed by structures whose parts are 
in motion, provided the similarity extends to the movements of similar parts; but 
the similar movements need not be simultaneous; they may, for example, resemble 
the rhythmically related movements of combined figure skating. 
The models employed to show the nature of the repetition in space which cha- 
racterises different types of homogeneous structure consist of symmetrically arranced 
dolls’ hands, the reason for employing these objects being that they are familiar and 
and at the same time of so exceptional a shape as to avoid any suggestion that a 
particular form is essential for the ultimate parts of a structure. 
Primarily the structures are to be regarded as not partitioned into parts, the 
type of homogeneity being expressed in a more general manner when there is no 
partitioning. 
The number of different types of symmetrical arrangement presented by all 
unpartitioned homogeneous structures is 230, 
As to the symmetrical partitioning of homogeneous structures the author points 
out that many different types of partitioning into molecular units are possible for 
each type of structure, and appends a fragment of a table of the types of partitioning 
which pertain to the different types of structure belonging to the cubic system. 
DEPARTMENT IT. 
1. Report on the Sizes of Pages of Periodicals. 
See Reports, p. 86. 
2. On Disturbance in Submarine Cables. By W. H. Prerce, 
C.Biy Holts 
This paper deals with the several problems connected with the difficulties in 
working sub-marine cables, and especially when used for telephonic purposes. It 
is fully reported in the ‘ Electrician’ for September 27, 1896. 
3. On Carbon Megohms for High Voltages. By W.M. Morpry. 
4, On an Instrument for measuring Magnetic Permeability: 
By W. M. Morpry. 
5. A Direct-reading Wheatstone Bridge. By A. P. Trorrer, B.A. 
The author describes a Wheatstone slide bridge which is made direct-reading 
upon a scale of equal parts. This is accomplished by making the ratio-arms of a 
1 Sohneke’s Entrichelung coner Theorie der Krystallstruktur, p. 28. 
