The reason for pouring boiling water into the tea-pot before the infusion of the tea is made, is, that the vessel being previously warm, may abstract less heat from the mixture, and thus admit a more powerful action. Neither is it difficult to explain the fact why the infusion of tea is stronger if only a small quantity of boiling water be first used, and more be added some time afterwards; for if we consider that only the water immediately in contact with the herb can act upon it, and that it cools very rapidly, especially in earthenware vessels, it is clear that the effect will be greater where the heat is kept up by additions of boiling water, than where the vessel is filled at once, and the fluid suffered gradually to cool.
When the infusion has once been completed, it is found that any further addition of the herb only affords a very small increase in the strength, the water having cooled much below the boiling point, and consequently, acting very slightly.
The ear consists of three principal divisions, viz. the external, intermediate, and internal ear. The different parts of the first division, or external ear, are described by anatomists under the name of the helix, antihelix, tragus, antitragus, the lobe, cavitas innominata, the scapha, and the concha. In the middle of the external ear is the meatus, or passage, which varies in length in different individuals. The external or outward ear is designed by nature to stand prominent, and to bear its proportion in the symmetry of the head, but in Europe it is greatly flattened by the pressure of the dress; it consists chiefly of elastic cartilage, formed with different hollows, or sinuosities, all leading into each other, and finally terminating in the concha, or immediate opening into the tube of the ear. This form is admirably adapted for the reception of sound, for collecting and retaining it, so that it may not pass off, or be sent too rapidly to the seat of the impression. There have been a few instances of men who had the power of moving the external ear in a similar manner to that of animals; but these instances are very rare, and rather deviations from the general structure; nor did it appear in these instances that such individuals heard more acutely: a proof that such a structure would be of no advantage to the human subject. With respect to the external ear in man, whether it is completely removed either by accident or design, deafness ensues, although its partial removal is not attended with this inconvenience: the external ear, therefore, or something in its form to collect sound, is a necessary part of the organ.