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CONTENTS. 
Page 
On Essentially Positive Double Integrals and the Part which they play 
in the Theory of Integral Equations, By H. BATEMAN............:c000000 447 
. “Operational Invariants. By Major P. A. MacManoy, F.R.S. ............ 449 
. A Method of obtaining the Principal Properties of the Exponential 
Function. By Professor A. HE. H. LOve, F.RS. .......cccceseccesecseneeseaee 449 
DEPARTMENT OF GENERAL PHYSICS. 
. The Transmission of the Active Deposit from Radium Emanation to the 
Anode. iBy) SIDNEY IRUSS, 15.) ser sccherasurp sakcene-ccsensanna ange aegeentaee 451 
. The Absorption of Gases by Charcoal. By Miss I. HOMFRAY...........0008 451 
. Report of the Seismological Committee (p. 83) .....ccsescseeceereeneenerseeeens 452 
. The Density of the Ether. By Sir Otiver Lopesk, F.RAS. ........ cece 452 
. An Electrical Experiment for illustrating the Two Modes of Condensation 
of Moisture on Solid Surfaces. By Professor F. T. Trovron, F.R.S. ... 458 
. On a Theoretical Method of attempting to detect Relative Motion between 
the Ether and the Harth. By A. O. RANKINE  ...........cccscccseeeeeereees 454 
. tOn the Nature of Ionisation. By Professor H. E. Armstrone, F.R.S, 465 
. Note on the Echelon Spectroscope and the Resolution of the Green 
Mercury Wine: by He STANSHTHED | oosescsces-cecetedessee-«srpanears semanas 455 
. The Production and Origin of Radium By Professor E. RurHERFORD, 
PTE: poeta scecasecasssseseaeasengrcaretencseseecarerss-as2n;raeqatace ae eee eee 456 
The Effect of High Temperature on the Activity of the Products of 
Radium. By Professor E. RurHerrorp, F.R.S., and J. E, Prravet, 
PEs er eta a sige in Se PROD Poe ghnc Sea's awnceskenncaass spnpa-<kde conte ponpepeneee enn 456 
On a Freehand Potential Method. By L. F. RICHARDSON ..........:s0e+00s 457 
TUESDAY, AUGUST 6. 
. Examples of the Modern Methods of treating Observations. By W. Patiy 
ED ERTON (5 on nsichnnnvaeas¥ awscpuntskontaani- causa Crts tena osueniudaiceys aieeiasasea 457 
. On the Use of Calcite in Spectroscopy. By Professor W. M. Hicks, F.R.S. 458 
DEPARTMENT OF MATHEMATICS. 
1. The Introduction of the Idea of Infinity, By W. H. Youne, Se.D., 
DPSECIS. ieee casctanasasasp'caamebucpceonensna ses de> cdkg ooops: <seey raaneenennena ane 458 
2. The Teaching of the Elements of Analysis. By C. O. Tuckny ............ 459 
3. On Models of Three-dimensional Sections of Regular Hypersolids in Space 
of Four Dimensions; By, Mis; A. B0OnH) STOUT .......:.ccassrates-ee seep saee 460 
4, Models of Three Developable Surfaces. By Professor SCHOUTE ..........+ 461 
5. On an Unrecorded and Remarkable Feature in the Splash of a Drop. By 
Professor A:...My WORTHINGTON, ['ESs..c0ccc-crss -naaneaen eon tecemeaes tecasenee 461 
G. A Property of Abelian Groups. By HaRorp HILTON ...........0.secceerene 461 
7. Factorisation of the Pellian Terms (r,, vn, &e.). By Lieut.-Colonel ALLAN 
OUNNINGHAM SH Hh aosesacceccsescscu-cctacsdoncansccdensteosceerersoonesaeaenspesess 462 
8) Report on’ Bessel Bunecbionsl(ps O4)\.2..cscdsees-snetinstuessatascenyossseeesonsens 463 
9. Regort on the Teaching of Elementary Mechanics (p. 97)..........sseceeeee0s 463 
