Eoyal Academy of Sciences and Literature of Brussels. S79 



in his recent improvements on ship -building, has profited much 

 by attending to this important difference. 



Some cylindrical pieces of iron ore from Marlborough Down, 

 commonlv known by the name of thunderbolts, were exhibited 

 to the Society. They have a stalactitical appearance, and are 

 radiated in their structure. By some they are supposed to be 

 pyritical. On analysis they are found to contain manganese as 

 well as iron, and when exposed to fire become of a reddish cast, 

 arising from tlie additional oxidation of the iron. The pieces 

 exhibited were a species of the brown hsmatitic iron ore. 



Mr. Rotch made some ingenious observations on lights and 

 shades, and illustrated the same by several curious experiments 

 made with four pieces of paper, so arranged and cut out, that 

 by the different intensities of light passing through, such a varia- 

 tion of light and shade was produced, as to form the most beau- 

 tiful and picturescpie landscapes. A gentleman had lately shown 

 Mr. R. a paper so cut, that the shadow formed on the wall pre- 

 sented an excellent representation of the Sulvator Miindi of 

 Guido. . . 



Tlfe meeting concluded by Dr. Wilkinson's examnuation ot 

 the different theories wliich'had been advanced for explaining 

 the phenomena of the Leyden phial. The Doctor endeavoured 

 to show from a variety of experiments, that the results could not 

 be reconciled with the theory of Dr. Franklin, or that which 

 supposes electricity to be a compound of two species, positive 

 and negative, or vitreous and resinous. The commuuication of 

 Dr. W.'s own theory v/as promised to be made at the next 

 meeting. 



ROYAf. ACADEMY OF SCfENCES AND LITKP.ATURE OF BRUSSELS. 



The Academy at a recent meeting proposed the following que- 

 stion ; , 7 /• 



" What are the applications uluch can be made oj steam 

 in domestic oeconomy, and in mamij'actures,as a means of heat- 



ing P" 



On this (juestion several memoirs have been presented ; on 

 examining whicii the Academy have awarded the prize of the 

 gold medal to one by M. de Ileniptinne, physician at Brussels, 

 as being the most distinguished both for practical detail and theo- 

 retical illustration. _ . . 



The following questions are proposed for competition durmg 



the year ISIS: r , • , jx 



1st. What are the particular defects of the sort of bricks mad* 

 in this country (Belgium) ? What means can be adopted to 

 render them more perfect ? What arc the materials and processes 

 employed in the northern provinces of the kingdom, for the fa- 

 ^ "' bncation 



