Page:Proceedings of the Royal Society of London Vol 1.djvu/117

Rh the continual repetition of these changes will likewise produce an equilibrium. According to these principles he undertakes to explain all the laws of increasing and decreasing heat; he supplies us with various examples as to the application of them, and shows how this theory coincides with the general law laid down in the ﬁrst part of the paper.

The drift of this treatise Will be still further illustrated, if we at- tend to the following recapitulation given us by the author of the leading principles deduced from the various parts of his investigation.

1. The effect of a constant source of heat upon the thermometer is not proportional to the heat of that source.

2. We nevertheless possess a method of determining the heat of the source by its effect on the thermometer, because we know the law this effect follows in its successive increments.

3. This method is the only one that ought to be employed when it is required to compare two sources of heat, according to their effect in a limited time, less than that which is necessary to produce the maximum of the effect.

4. In the case of transmitted heat, we must distinguish that which is immediately transmitted, from that which is added by the trans- mitting body after it becomes heated. .

5. If we neglect making the distinction, the interception of heat attributed to the intercepting body is only an inferior limit or mini- mum; so that it remains undetermined whether the interception has not been much greater, or even total.

6. By applying these principles to Dr. Herschel's experiments, a more exact appreciation may be obtained; it is, however, governed by some accessory circumstances, which have not yet been deter- mined.

7. In those experiments the apparent difference between the in- terception of heat and of light by the same substances, does not af- ford any fair conclusion respecting _the difference or the identity of light and heat. 7

8. The law mentioned in the ﬁrst part of the paper is not only proved by direct experiments, but also by its agreement With the true theory of the earth.

Lastly. This theory is established upon various facts, entirely dif- ferent from the above law, and it is the only one which agrees with the general phmnomena of nature.

This, it is to be observed, is only the first part of a more extensive work, and relates merely to the rectiﬁcation of the hyperbola. After a few strictures on the necessity of not relaxing in our endeavours to improve the method of ﬂuxions, to which the author asserts few additions have been made since its first discovery by the immortal