i8o 



NATURE 



[June, 2 1. 1900 



machine, or of the motor or other appliances connected with the 

 working of the same. The light given by the tubes was per- 

 fectly steady, which is one of the advantages usually claimed for 

 the influence machine over the coil, although this has been 

 somewhat diminished since the advent of the Wehnelt and 

 Caldwell electrolytic breaks. 



Mr. J. WiMSHURST, F.R.S., also read a short paper on his 

 work in connection with the design and perfecting of the 

 several forms of his influence machine, describing, among 

 others, the large machine made for and presented to the Science 

 and Art Department, with plates 84 inches in diameter ; and 

 another, with twenty-four plates 36 inches in diameter, shown at 

 the Earl's Court Exhibition, and which is now, we believe, in 

 the possession of Dr. J. Macintyre, of Glasgow. — Dr. Remy, of 

 Paris, showed a new localising apparatus. This consists of a 

 vertical support moving in a socket fixed to the table. The 

 tube is supported by a cross piece at the lower end, under the 

 table, while the fluorescent screen is attached to the upper end, 

 together with two pointers representing the paths of the rays, 

 and held in supports moving in slots or grooves. Two observa- 

 tions are made and the pointers adjusted, after which the 

 apparatus is turned round away from the table, and the pointers 

 lowered until their points meet, thus indicating the df pth of the 

 hidden object below the surface. A bullet hidden in a loaf of 

 bread was found in a minute or so by Dr. Remy. 



The Scientific American contains an account of Count von 

 Zeppelin's projected navigable balloon now under construction 

 on Lake Constance. The balloon is to be 416 feet in 

 length and 38 feet in diameter, divided into seventeen compart- 

 ments, and supported on an aluminium framework. It is to 

 carry two cars and motors, and to be propelled by screws placed 

 in pairs at the side of the balloon and geared to the driving- 

 shaft by two diagonal shafts. In the preliminary experiments 

 for testing the efficiency of the motors, a launch was driven 

 on the lake at from 6'S to 9-2 miles an hour by aerial 

 propellers. The fuel is benzene, and it is calculated that the 

 balloon will carry sufficient fuel to perform a journey of over 

 179 miles. 



The cutting of the sudd on the Upper Nile and the conse- 

 quent release of large volumes of stagnant water has, we learn 

 from the Times ,\\z.d. an unanticipated influence on the condition 

 of the river at Assuan. P'rom reports received by .Sir Benjamin 

 Baker from the engineering staff" it would appear that the 

 absence of free oxygen in the water has caused wholesale 

 destruction of the fish. Within a hundred yards of the 

 resident engineer's office at least a million dead fish, ranging in 

 size from minnows to six feet in length, are to be found. This 

 result is consistent with London experience when it was usual 

 to pour crude sewage into the stream. The filtered water, 

 though clear and odourless, was drunk with impunity, but, 

 having no free oxygen, eels plunged into it would struggle 

 violently and finally die of suffocation, as has apparently been 

 the case with the fish in the Nile in the special circumstances 

 resulting from the long-deferred cutting of the sudd \}cv\s, year. 



Some notes on New Zealand volcanoes are contributed to 

 the latest volume (1899) of Transactions and Proceedings of the 

 New Zealand Institute, by Dr. B. Friedlander. A description 

 of an eruption of Te Mari witnessed by him is of interest. The 

 eruption began with an explosion, and masses of ash-bearing 

 steam were ejected. There were at least four different light- 

 phenomena :— (l) the reflection of incandescent matter upon 

 the dark clouds ; (2) a large number of red-hot boulders, which 

 were shot high up and fell down in parabolic curves ; (3) light- 

 NO. 1599, VOL. 62] 



ning, due to electricity produced by friction. The lightning 

 appeared in masses of ash-bearing steam ; and the ashes were 

 coarse, the single grains being about the size of a pin's head. 

 (4) Blue flames, and probably- reddish flames. Some red flames 

 were apparently distinct from the light due to illumination of 

 steam, and the blue flames must have been real. Dr. Fried- 

 lander suggests, to account for the flames, that during the 

 explosion there escaped combustible gases which at a certain 

 height above the crater met the oxygen necessary for taking 

 fire. He considers that vaporised sulphur would explain his 

 observations better than hydrogen, the flames of which are less 

 brilliant and less distinctly blue. Another paper of interest to 

 students of vulcanology, in the volume referred to, is a detailed 

 description of the volcanoes of the Pacific, by Mr. Coleman 

 PhiUips. 



An official report by Captain R. H. Elliot, upon his re- 

 searches into the nature and action of snake-venom, is referred 

 to in the Madras Mail. Captain Elliott confirms the fact that 

 the mongoose is not immune in the fullest sense of the expres- 

 sion, seeing that it may succumb to a snake-bite, if sufficiently 

 severe, like any other animal. His researches go to show, how- 

 ever, that the mongoose does enjoy a partial and comparative 

 immunity from snake-poison — that is to say, a mongoose takes 

 from ten to twenty-five times as much cobra venom to kill it 

 as a rabbit does, and five to twelve times as much as a dog. 

 M. Calmette gives a somewhat lower estimate than this ; but 

 he made only a few experiments, and it is noteworthy that the 

 mongooses that he experimented with were obtained from 

 Guadeloupe, where venomous snakes are unknown. The mon- 

 goose was introduced into Guadeloupe (and Barbadoes) some 

 twenty-five years ago with a view to the destruction Of rats. 

 Captain Elliott thereupon remarks : — " We are thus led to the 

 interesting conclusion that the introduction of the mongoose 

 into a country in which venomous snakes are unknown has re- 

 sulted, in so short a period as a quarter of a century, in a very 

 appreciable reduction of the animal's resistance to snake-venom. 

 This fact points strongly to the farther conclusion that the im- 

 munity is an acquired one, and inasmuch as the acquired 

 characteristic has been so rapidly and easily diminished, it 

 would appear likely that it must be maintained from generation 

 to generation. Be it remembered that a quarter of a century 

 probably means about fifty generations." 



The growing necessity of obtaining greater speed on rail- 

 ways has of late been freely discussed, and different designs 

 have been put forward favouring very much the idea of a single- 

 rail system resting on supports and its train suspended below. 

 Hitherto all railways of this nature have been propelled by steam 

 or electric motors, but Fie/dens Magazine (June) describes and 

 illustrates a still later application of this suspended car system, 

 patented by Mr. H. S. Halford under the name of the Halford 

 gradient railway. The remarkable feature about his system is the 

 fact that no locomotive or electric motors are carried, as the train 

 derives its motion by gravitation imparted by raising, as long as 

 this is required, to a slight incline, the section of line upon which 

 the train is running. The track of this railway, which is sup- 

 ported, is divided into sections, the extremities of which can be 

 raised or lowered by hydraulic (or other) power, the operation 

 being performed either automatically by the carriage in its transit 

 or by the driver at will. It is stated that the cars ride smoothly 

 going from one section to another, and also the change of incline 

 is so small and gradual that the lifting of the track is almost un- 

 perceived. The Halford gradient railway has yet to see a more 

 practical test, but the following advantages claimed make the 

 devise feasible in many ways :— (i) In all other systems, the 

 greater the load the less the speed ; in this, the greater the load 



