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Queries and Answers. 



will be less ami less bent when they enter his eye : consequently, the ima- 

 ginary water will recede to a greater and greater distance, diminishing also 

 m extent. As he sinks down, the reverse will take place : fewer and fewer, 

 and at last no direct rays from the hill will reach him, while the refracted 

 rays from the sky will arrive more and more bent : thus bringing the watery 

 appearance nearer and nearer ; till, finally, when his head is close to the 

 ground, every terrestrial object, except the spot on which he is placed, will 

 disappear, and he will find himself totally enveloped in what will seem 

 tremulous white vapour. — A Subscriber. March 23. 1830. 



T/ie Weather; in answer to Mr. Gorrie. — Sir, Your valuable correspond- 

 ent Mr. Gorrie (Vol. II. p. 177.) has proposed a few very natural and curious 

 questions, which, if satisfactorily answered, may afford some amusement to 

 your readers. His questions, in their order, are, first : — 



" Why is the awn of the wild oat, &c.,more straight when the hygrometer 

 indicates saturation than when the air contains less moisture ? " To answer 

 this, a short description of the awn of %the oat must first be given. It 

 is composed of two parts, a spirally formed base and a simple bristle-like 

 apex : the former is contracted by a rotatory motion in damp, and relaxed by 

 a contrary motion in dry, air. The like effects are observable on all cordage, 

 string, and every description o^ twisted material. The water received among the 

 plications of the tissue swells the threads of which it is composed : of course, 

 each thread is forced from its longitudinal to a more transverse position, 

 thereby increasing the diameter of the cord, while it reduces its length. It is 

 on account of this property that whipcord, catgut, string, &c., have been used 

 to form common hygrometers; and some of the most delicate instruments for 

 indicating the state of the air, as to moisture, are formed of the spiral base of 

 the wild oat. To be convinced of this moving power of the awn, let the natu- 

 ralist separate one from the ear, and, holding the base between his finger and 

 thumb, moisten the awn with his lips : it will be seen to turn round for some 

 time ; which motion is caused by the collapsing of the volutes of the spiral 

 base. That the awns are all more straight, and mostly pointed in one direction 

 in damp weather, is perfectly true : they are so, because they are coiled up as 

 in fig. 123. a; whereas, when the air is dry, they are relaxed into the form b. 

 The use of the aristee, or awns, in vegetable econo- 

 my, is supposed to be for the purpose of attracting 

 or discharging electric currents necessary for either 

 the protection or maturation of the plant. 



Mr. Gorrie's second question relates to the 

 collapsing of the flowers and leaves of plants 

 before rain. Many plants, and particularly those 

 named in the question, take a kind of repose 

 during the night. The light and heat of the sun 

 are the stimulants to their rigid expansion and de- 

 velopement : but when his influence is withdrawn 

 during night, or partially during the day, the petals 

 of flowers contract, and the petioles of leaves lose their rigidity, or relax in 

 a contrary direction to what they had in the day ; and as rain is commonly 

 preceded by a lower temperature and clouded sky, the plants affected by the 

 direct influence of the sun are soon sensible of the deprivation, and droop or 

 collapse accordingly. Light is, therefore, the principal cause of expansion, 

 and the want of it occasions flaccidity. Even artificial light will open flowers 

 that have shut themselves up for the night : a crocus has been expanded 

 by the light of candles ! On this subject it is necessary to add a few re- 

 marks, viz. : — Some flowers and leaves seem to be affected by the light, 

 and others chiefly by the heat, of the sun ; if, however, they receive either 

 too intensely, they suffer and are withered. Instead of a temporary cessa- 

 tion of their vigour, as is the case before rain, it is an injury which only a 

 refreshing shower and darkness can recover. Again, many plants are most 



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