136 



NATURE 



[Dec. 8, 1887 



the lapse of a day was born a young one, which possessed 

 in its uterus an ovum already in segmentation. From 

 this ovum two days later was produced a third female, 

 while a second ovum in the uterus of the mother was 

 also already commencing to segment. Whether all 

 the "summer" (parthenogenetic) eggs develop into 

 females or not, has yet to be proved. Here also it was 

 shown that one polar body was extruded. 



The second part of the memoir sums up the literature 

 relating to the subject, with the result that the extrusion 

 of two primary polar bodies from fertilized ova has been 

 demonstrated in sixty-six cases, that of one only from 

 parthenogenetic ova in fourteen cases ; while none of the 

 few observers who describe the extrusion of one polar 

 body only from a fertilized ovum, have endeavoured to 

 show that a second one may not have been present, at an 

 ontogenetic period other than that which they describe. 



G. Herbert Fowler. 



SIEMENS' S GAS-BURNERS. 



OWING to the very high temperature of ignition of 

 gas, the only way in which it can be successfully 

 used with the greatest economy is by the application 



of regenerators. This was proved practically by the late 

 Sir William Siemens in carrying out his own and his 

 brother's invention of the regenerative gas-furnace. For 

 more than eight years now Mr. Frederick Siemens has 

 devoted a portion of his attention to the domestic applica- 

 tions of gas, and he has quite recently opened a depot in 

 the Horseferry Road for the sale of his gas-lamps. Here, 

 on Tuesday afternoon, he entertained several gentlemen 

 interested in gas illumination, and tested photometrically 

 some of the burners we propose to describe and 

 illustrate. 



It is well known that the light intensity of a flame 

 increases with its temperature in a higher ratio than the 

 arithmetical, although the actual ratio has not been abso- 

 lutely determined. It is, moreover, known that the more 

 the energy of flame is transformed into radiant light and 

 heat the less is the amount carried away in the products 

 of combustion. But the difficulty is to take advantage of 

 these laws in practice, and to combine high temperature 

 with durability, and the use of regenerators with simplicity 

 of arrangement and elegance of appearance in the lamp. 



After the Smoke Abatement Exhibition, at which Mr. 

 Frederick Siemens's regenerative gas-lamps were for the 

 first time exhibited in this country, a great outcry was 

 raised on account of their unsightliness. The economy 



Fig. I. 



of the light and its intensity were in vain dwelt upon : 

 the British public were not inclined to entertain the new 

 lamps, and a comparatively small business was done in 

 them. Besides this, it was discovered by degrees that 

 when impure gas was employed the gas passages became 

 blocked with a sulphurous deposit, so that, in order to 

 maintain their high efficiency when in constant use, these 

 passages had from time to time to be cleared. Mr. 

 Siemens set to work to overcome both these defects, 

 and the lamps he has now produced lend themselves to 

 artistic ornamentation, and have no passages to offer 

 obstructions to gas of ordinary quality. 



The lamp we propose to describe in the first instance 

 is the one known as the open-flame sunlight pattern. 

 It is designed for use in positions where the ordinary 

 sunlight lamp is employed, such as public halls, concert, 

 dining, and billiard rooms, banks, and theatres. The 

 flame in this lamp is extremely delicate and elegant in 

 appearance, having the form of an inverted cone of light, 

 apparently unsupported. The annexed drawing illustrates 

 the construction of this lamp. Four hoods made of suit- 

 able material are arranged one above the other so as to 

 form passages through which the products of combustion 



Fig. 2. 



are removed, their waste heat being utilized to heat the 

 air supplied to the flame. The jets of flame issue in a ring 

 from the lowest hood ; the products of combustion, passing 

 through the aperture O, are drawn downwards through the 

 annular space B, and then upwards through c to the 

 chimney E. The hood between the passages A and B is 

 intensely heated by the products of combustion descend- 

 ing on its upper surface ; and the air which travels through 

 the annular space A, on its way to supply the gas-jets, 

 takes up the heat from the hood, the flame being thus 

 supplied with heated air, as well as burning in an in- 

 tensely hot atmosphere. The lamp we were shown con- 

 sumes 24 cubic feet of gas per hour, and gives, with 

 ordinary London gas, a light equal to 180 sperm candles, 

 or 7*5 candles per culjic foot of gas, which is more than 

 twice the light obtainable from the same amount of 

 gas burnt in ordinary burners. This lamp was set up 

 with a ventilator, but was much too brilliant for use in 

 the room in which it was exhibited, the ceiling being 

 only about 12 feet above the floor, whereas it should 

 be placed at an elevation of 30 feet or more, when it 

 would not only serve for illuminating-purposes, but also 

 for those of heating. 



