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VI. Lagrange’s Ballistic Problem. 
By A. E. H. Love, F.R.S., Seclleian Professor of Natural Philosophy in the University 
of Oxford, and F. B. Pidduck, M.A., Fellow of Queen's College, Oxford. 
Received June 3,—Read June 30, 1921. 
[Plates 1 and 2.] 
Contents. 
PART I. 
Article. Page. 
1. Introduction.168 
Theory op Plane Waves op Finite Amplitude. 
2. General Equations.170 
3. Progressive Waves.171 
4. Motion of a Junction.172 
5. Nature of the Motion in a Compound Wave.173 
6. General Analysis of Compound Waves .. 174 
7. Relation between Pressure and Density.175 
8. Integration of the Equation in Special Cases.176 
9. More General Integration.176 
The Progressive Waves in Lagrange’s Problem. 
10. The Progressive Wave from the Left.177 
11. The Progressive Wave from the Right. 179 
The First Middle Wave. 
12. Conditions satisfied at the Receding Front.180 
13. Conditions satisfied at the Advancing Front.181 
14. Conditions determining the First Middle Wave.181 
15. Determination of the First Middle Wave.182 
16. Transformation of the Formula.184 
17. Incidence of the First Middle Wave on the Pistons.185 
VOL. CCXXII.-A 599. 2 B [Published March 6, 1922. 
