পাতা:পদার্থবিদ্যাসার.djvu/৭৫

64 Pup. Is the hair of the head merely ornamental ? Tut. No. It not only keeps the head warm, it serves to keep open its pores, and let out the evaporations through their own hollow tubes : and serves also for its defence from violence Pup. Are the hairs hollow Tut. Yes, this you may see with the microscope. Pup. What have you to telt me of the eye ? Tut. It is one of the most artfully constructed parts of the human body. Leaving the internal construction of the eye to the anatomist. I shat! now only make the following remarks: The eye is moveable in its socket, that we may be able to see on three sides without moving the head. By its position, it is well secured from injury : when we have too unuch light, it has the power of contracting the apple or pupil of the eye, so ward off its too numerous rays : and again, when there is but little light, then it can enlarge it to receive more rays. Pup. Of what service are the eyelashes ? Tut. To moderate the strong light, and to preserve the eye from flying insects. Put. Of what particular service is the eyelid 2 Tut. The eyelid is as a curtain, to be drawn up by day, and to be let down at night when we sieep, that we may enjoy our rest with greater security. Pup. What is the benefit of the eyehrow ? Tut. It is wisely formed to keep off the dust and sweat, which would give the eye exquisite pain, beside being detrimental to sight. It defends and cleans the èye at the same time. r