394 Analyses of Books. [May 



editor of this journal, it is stated, that of 3700 specimens of flowers 

 examined by him, 3628 had all the characters of Tormentilla, 43 

 possessed those of Potentilla, while the remaining 29 varied in the 

 number and proportion of the divisions of the calyx and corolla. 

 From whjch it would appear, that the genus Tormentilla, as was 

 maintained by the accurate Sir James Smith, does exist, and that 

 the occasional multiplicity of petals and sepals is to be referred to 

 luxuriance of growth. 



Mr. W. Baird iu a notice of the aurora borealis mentions, that on 

 one occasion, when this phenomenon was remarkably vivid, he thought 

 he heard a momentary sound resembling the noise produced by the 

 quick flight of a bird over head. 



Dr. Johnston describes and figures three Roman urns of coarse 

 clay, which were dug up near Berwick. He considers them ^to 

 possess all the interest attached to antiquities of 1400 years existence. 



This number terminates with a list of additions to the Flora of 

 Berwick, which have been made since the publication of Dr. John- 

 ston's Flora. 



We would heartily recommend to naturalists in provincial parts 

 of the country, the establishment of societies like the club of Berwick- 

 shire, because we are convinced, that they will tend to nourish that 

 scientific spirit, which for want of due encouragement is too often 

 blasted'in the bud. 



IV. — Abstract of a Paper on the Refraction and Polarization 

 of Heat. By Professor Forbes. (Read before the 

 Royal Society of Edinburgh on 29th January 1835.) 



The First Section of this paper contains an account of a variety of 

 experiments undertaken with the thermo-multiplier of Nobili and 

 Melloni, the instrument exclusively employed in the subsequent re- 

 searches. By a comparison of its sensibility with that of air ther- 

 mometers, the author concludes that one degree of deviation of the 

 needle of the multiplier corresponds to an effect indicated by about 

 one-fiftieth of a centigrade degree on the others. Without increas- 

 ing the dimensions of the multiplier, by which its sensibility would 

 be impaired, he has been enabled, by an optical contrivance, readily 

 to measure one-tenth of one of its degrees, corresponding to one-five 

 hundredth of a centigrade degree. From an experiment intended 

 to detect the heat of the lunar rays, concentrated by a polyzonal lens, 

 thirty-two inches in diameter, and acting upon this instrument, he 

 concludes that the direct effect of the moon upon an air-thermometer 

 probably does not amount to one-three ^hundredth thousandth part 

 of a centigrade degree. 



After mentioning his repetition of M. Melloni's experiments upon 

 the refraction of heat, the author proceeds, in the Second Section, to 

 give an account of his own researches on the action of tourmaline on 

 heat. At first he found (as it afterwards appeared M. Melloni had 

 done) that no more heat was stopped when the tourmaline plates 

 had their axes crossed, or transmitted least light, than when they 

 were parallel, or transmitted most. He afterwards detected a fal- 



