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Vice-President, said there were Sir Benjamin many works in the field of investigation covered by the Paper, but there was hardly any investigator entitled to speak with greater authority on the subject, on the basis of practical experience, than the Author. He had, therefore, great pleasure in asking the members to accord him a very hearty vote of thanks for his valuable Paper.speaking, in the latter part of the Paper, of a Cornish cycle, he did not mean a Cornish engine.With reference to the mode of analysis of indicator-diagrams he had selected, any errors in the system which did not appear to have any material effect in vitiating the comparative results had been neglected. The object of the Paper was to make comparisons. In Fig. 2 it would be seen that the enclosing diagram should be longer than the enclosed diagram ; therefore the energy to be obtained from the enclosing diagram was measured, not only by the average pressure of the diagram, but by its length; and as it was longer than the indicator-diagram, if that error were corrected it would make what he had called the engine-efficiency somewhat lower. It would do so, however, in all the examples throughout the series, and it would not materially affect the comparative results. Again, he had pointed out that compression influences, when considerable, should be taken into account ; but he had not thought it necessary to calculate all those influences, because the percentages would be similar throughout the series. He wished to emphasize the fact that the foundation of the Paper was a comparison of results. A t absolute results he had not attempted to arrive. comparisons made in the Paper between engines of different types ; but he could not help calling in question the standard with which comparison had been made. It had been stated by the Author that he meant "the actual power developed compared with the power theoretically possible under the-given conditions of initial pressure and expansion." The ratio of expansion was not fixed by the conditions, as the available range of temperature was, but was within the discretion of the engine-designer ; it was one of those points which the standard had to try. If the standard was adjusted to suit the conditions, by varying the assumed ratio of expansion,

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