246 WHY NOT HAVE GOOD TEETH? 



face toward the iDtcrnal parts. If one or some of them are in some state 

 of weakness, danger or bad consequences cannot fail. It is the same thing 

 as Math a large quantity of cold water taken in too quickly when the body 

 is heated. A draught, then, is injurious only in so far as it causes perturba- 

 tions in our heat-economj^, and as these pcrtubations can be caused in differ- 

 ent ways wc often accuse the draught wrongly. 



"We hear often, "I don't like sitting near this window, close to this wall," 

 and so on; "there is always a slight draught coming from there." We 

 fancy that we feel the draught, the motion of a wind, but it is mostly increase 

 of one-sided heat-loss by radiation toward the cold place. People generally 

 believe, rather, that the wind comes through the wall. But the velocity of 

 such a wind is too small to be felt as air in motion, and a piece of carpet 

 fixed to the suspected wall does away with the supposed draught. It could, 

 therefore, not be caused by the air-rush through the wall, because the carpet 

 is many times more permeable to air than the wall. 



I hope, in future, ventilation and draught will be to your mind two dis- 

 tinct things. — Pettenkoper, in Popular Science Monthly. 



WHY NOT HAVE GOOD TEETH? 

 BY A. HOMER TREGO, D. P. S. 



There is scarcely a subject of a personal character so sadly neglected 

 and so little understood, by the people in general, as the care of the teeth. 



In view of this fact, in 1869 the Odontographic Society of Philadelphia 

 (about 100 members of erainerrt ability) offered a prize for the best essay on 

 the subject; the same to be published for the benefit of the public. 



The prize Avas awarded for the following: 



RULES FOR PRESERVING THE TEETH, 



1st. Cleanse your teeth once, or oftener, every daj^ ! Always cleanse them 

 before retiring at night! Always pick the teeth and rinse the mouth after 

 eating ! 



2nd. Cleansing the teeth consists in thoroughlj' removing every particle 

 of foreign substance from around the teeth and gums. 



3rd. To Cleanse, use well made brushes, soft quill or wood toothpicks, an 

 antacid, styptic toothwash and precipitated chalk. If these means fail aj)ply 

 to a reliable dentist. 



4th. Alicays roll the brush up and down lengthwise of the teeth, by 

 which means you avoid injuring the gums and necks of the teeth, and more 

 thoroughly cleanse between them. 



5th. Never use a dentifrice containing acid, alkali, charcoal, soap, salt, 

 or any gritty or powerful detersive substance. 



6th. Powders and pastes generally arc objectionable. They injure the 

 gums and soft -parts of the teeth, and greatly assist in forming tartar. A 



