May 8, 1902] 
‘A HISTORICAL account of the discovery of voltaic electricity 
is contributed to Nos, 642 and 643 of Prometheus by Dr. F. 
Dannemann. It deals chiefly with the discoveries of Volta, 
Galvani, Oersted and Ampére, and the author considers that at 
the beginning of the twentieth year of the nineteenth cen- 
tury the chief fundamental facts concerning electricity had been 
made known with the exception of induction, which was left for 
the genius of Faraday to discover. 
| Suffolk House.” 
NATURE 
Tue tendency of streams to diverge from a straight path and | 
to assume a zigzag course forms the keynote to a paper by Mr. 
Lewis B. Haupt, on single curved wersws double straight 
jetties, in the Journa/ of the Franklin Institute for April. 
Where a river assumes a sinusoidal form. there is a constant 
tendency of the current to eat away the concave banks and to 
deposit silt on the convex ones, and the author considers that if 
this natural tendency is counteracted by confining the stream 
between two parallel straight jetties, much expense in dredging 
out the river bed will be incurred, whereas the construction of a 
single wall at the concave side of bends will enable Nature to 
do her own work by keeping the channel scoured at the side of 
the wall and forming a convex training bank at the other side. 
This method has been tried with success at Aransas Pass in 
Texas, and the author is of opinion that single concave reaction- 
jetties may economically be adapted to the opening of the 
delta mouths of silt-bearing streams. 
A sHorT note in the Journal of the Royal Microscopical 
a 
39 
Suffolk, in the reign of Henry the Eighth, which was called 
From Antony van den Wyngaerde’s ‘* View 
of London,” circ. A.D. 1550, which contains the only repre- 
sentation of the house known, it appears that the mansion was 
built in the style of the early Renaissance, and it therefore seems 
very probable that the fragments in question had their origin in 
Suffolk House. 
THE number of new species of American butterflies, mostly 
from Brazil, described by Mr. W. Schaus in No. 1262 of the 
Proceedings of the U.S. Museum (vol. xxiv.) may be taken as 
an indication of the large amount of work which remains to be 
done in South American entomology. 
In Naturwissenschaftliche Wochenschrift of April 27, Mr. 
C. Frings gives a véswmé of the experiments made by Dr. 
Standfuss on hybridising Lepidoptera and the influence of 
temperature on the development of the pupa, to which allusion 
has been made in these columns on a previous occasion. 
Onr of the most remarkable architectural structures in exist- 
ence is the left-handed spiral staircase in the Chateau de Blois, 
Touraine, built during the sixteenth century from designs by ~ 
Leonardo da Vinci. Ina well-illustrated and thoughtful article 
published in the May number of the Monthiy Review, Mr. 
Theodore Cook shows that the design of this staircase corre- 
sponds so exactly with the spirals on the common Mediterranean 
| shell known as Voluta vespertilio as to leave little doubt that 
Society, on a paper by Mr. G. Marpmann on distinguishing | 
between Pleurosigma angulatum and P. balticum under low 
powers, may well suggest an interesting field of observation in 
the diffraction colours of some of the more regularly marked 
diatoms, and the possibility of measuring the striations of the 
valves even by naked eye observations. By holding a slide 
thickly spread with any species of the genus Pleurosigma in full 
sunshine, it is easy to trace the diffraction colours through the 
various tints of the spectrum from violet to red and even to 
follow the second diffraction spectrum down to the green, and 
itis possible in this way to go further than Herr Marpmann 
would appear to have done so far as can be gathered from the 
note. in question. If a slide of Plewrosigma angulatum or 
quadratum is held up in a bright light and a few of the much 
more coarsely marked P. da/ticum happen to be mixed with the 
other diatoms, the latter forms, by the different colours which 
they exhibit, are easily discernible to the naked eye. Two 
other papers allied to the above are also noted in the same 
journal, one by Mr. W. Balfour Stokes, who concludes that the 
minute perforations in Plewros7gma formosum are silted up with 
silica, and one by Mr. J. Rheinberg, who has succeeded, by 
placing a disc of a certain form above the objective of his micro- 
scope, in obtaining two images of the same diatom in comple- 
mentary colours, one being a dioptric image and the other a 
diffraction image of the first order. 
In the course of excavating in the churchyard of St. George 
the Martyr, Southwark, in connection with the Long Lane 
street improvement, now being carried out by the London 
County Council, a very interesting discovery has been made. 
At a depth of about nine feet, some fragments of pottery and of 
ornamental terra-cotta work were discovered in a heap, as if at 
some time or other they had been thrown together promiscu- 
ously. The fragments were exhibited at a meeting of the Society 
of Antiquaries on April 17. Whilst the pottery is Roman, the 
terra-cotta work, the ornamentation of which is peculiar, dates 
from the time of Henry VIII., in whose reign the art was intro- 
duced into England. Stow says that ‘‘almost directly over 
against St. George’s Church, was some time a large and most 
| origin of the design. 
sumptuous house, built by Charles Brandon, late Duke of 
NO. 1697, VOL. 66] 
the artist had that shell before him as his model. The spiral 
on the central column of the core of the staircase corresponds 
exactly, for instance, with the spiral ridges on the columella of 
the volute, as seen in section. This of itself would be strong, 
although perhaps not absolutely convincing, evidence as to the 
But the staircase has also an exquisite 
outer balustrade, which shows a correspondence to the coils 
on the external spire of the shell as close as that which obtains 
between the interior of the staircase and the columella of the 
volute. Such a dual resemblance could scarcely be the result 
of coincidence, and the author seems therefore to be justified in 
the view he has taken. It is remarkable, however, that the 
spirals in the staircase run in the reverse direction to those in 
normal examples of the shell, that of the central shaft being 
left-handed instead of right-handed. The spirals are, in fact, 
those of a ‘‘reversed,” or dextral, example of the shell, of 
which, perhaps, one in a million occurs in nature. That 
Leonardo da Vinci had such a reversed shell from which to copy 
is unlikely ; but it is known that he was left-handed, and a left- 
handed man would naturally draw a reversed spiral. The 
author, we believe, has in hand a work on natural spirals in 
general. 
Tue April number of the Kecord of Technical and Secondary 
Education contains an important review, by Mr. W. M. Webb, 
of the means taken by the different County Councils in Eng- 
land for training teachers in the best methods of imparting 
“ nature-knowledge” to their pupils. The prime object of 
such teaching is, of course, to make the pupils conversant with 
natural things by seeing and handling them in their own sur- 
roundings, and for this purpose field-excursions are absolutely 
necessary. Some educationists would indeed _ reserve - the 
American term ‘‘nature-study” for observations of this class 
in which the relationships of animals and plants is not the main 
point of instruction. But such studies cannot be altogether 
separated from systematic biology, and the value of a thorough 
biological. groundwork to the teacher is accordingly emphasised 
by the author. Prof. Bailey’s leaflets, which have been adopted 
by the Board of Education as a basis of nature-study, are 
insufficient if systematic biology is to be really taught, and 
short courses on the best methods of teaching natural history 
