I30 



SCIENTIFIC NE'\VS. 



[Aug. 1st, iS 



not be disproved by any number of cases of bald men who 

 don't wear wigs. 



Other pigments besides haemoglobin occur in the bodies 

 of animals, and some of these appear to have a respiratory 

 function, e.g., the blue pigment found in some mollusks, and 

 the purple pigment of bugula and some sponges. Kuhlmann 

 has shown that cochineal solutions have some power of 

 taking up oxygen and parting with it again, and that they 

 deepen or pale in colour in consequence. It may turn out 

 that both cochineal and the very similar lac-dye serve as 

 respiratory pigments to the insects which form them, but it 



DRIVING DYNAMOS WITH SHORT 

 BELTS. 



PROFESSORS AYRTON and PERRY recently read a 

 paper on the above subject at a meeting of the 

 Society of Telegraph Engineers and Electricians, and as 

 many of our readers are interested in the driving of dy- 

 namos for electric lighting, we give an illustration, which 

 will enable them to understand clearly what is now pro- 

 posed. We are all familiar with the horizontal belting 

 generally used, but such an arrangement is almost im- 

 possible on board ship, or wherever the space available is 



DvNAiMo Electric Machine driven with a Short Belt. 



is useless to speculate upon facts which are as yet imper- 

 fectly ascertained. 



To readers of a practical turn of mind the great economic 

 value of cochineal, the abundant supply of haemoglobin, and 

 those resemblances between cochineal and haemoglobin 

 which have already engaged the attention of chemists, will 

 perhaps suggest that heemoglobin may some day be put to 

 industrial use. The indications are not very decided as yet, 

 and it is pretty safe to venture the opinion that the interest 

 of hasmoglobin will long continue to turn exclusively upon 

 its physiological office. 



confined, and a short belt would always be employed were 

 it not that the small angle of contact of the belt with the 

 driven pulley would then necessitate the tension on the belt 

 being excessively great, to ensure sufficient grip for driving. 

 The increased tension would cause excessive pressure on 

 the bearings, and this would not only involve waste of 

 power, but also frequent stretching of the belt and in- 

 creased wear. 



In our illustration, D is the dynamo, L its driven pulley, 

 and F, the driving pulley, or fly-wheel of an engine. The 

 fixing of the dynamo is peculiar, and on this depends the 



