666 Chronicles of Science. | Oct., 
that used by the inventor, John Dolland, in 1758. A form adopted 
by Steinheil in 1860, computed from a paper by Gauss published in 
1817, is spoken of very highly as admitting of an increased aperture 
for a given focal length. With reference to the discovery of achro- 
matism, it is an interesting fact that in a curious old folio volume, 
entitled ‘Zahn’s Optics, printed at Nuremberg in 1702, amongst 
other diagrams one is given of a pair of lenses exactly similar to an 
achromatic object-glass of the form adopted by Dolland. Mr. Hodgson 
speaks in high terms of the regularity and great excellence of the 
optical glass now made by Messrs. Chance, of Birmingham. 
The Rev. W. R. Dawes has announced the curious fact, that the 
small star s. p. ~ Herculis, which in the year 1856 was discovered by 
Mr. Alvan Clark to be close double, is a binary system, the variation 
in position amounting to about 18° within the last five or six years. 
Mr. Pogson now considers that the identity of his last new planet 
with Freia is quite established, and the name Suppho is again at 
liberty for future use. He has now provided another candidate for the 
name, this time most certainly and evidently a new planet. Its 
magnitude is 10-4. 
Mr. De la Rue reports most favourably of the performance of a 
telescope of new construction, sent by Dr. Steinheil for exhibition at 
his reception held at Willis’s Rooms on June 11. The objective has 
an aperture of about 4:2 inches, and a focal length of about 40 inches. 
Dr. Steinheil is now engaged upon an object-glass composed of three 
lenses of 6 inches aperture, and only 30 inches focal length. 
Ill. BOTANY AND VEGETABLE PHYSIOLOGY. 
Dr. Asa Gray makes the following remarks in regard to Calluna 
vulgaris as en American plant :— 
The earliest published announcement that we have been able to 
find of Calluna vulgaris as an American plant is that by Sir William 
Hooker, in the Index to his ‘ Flora Boreali-Americana’ (ii. p. 280), 
issued in 1840. Here it is stated that—‘‘ This should have been in- 
serted at p. 389, as an inhabitant of Newfoundland, on the authority of 
De la Pylaie.” Accordingly in the seventh volume of De Candolle’s 
‘Prodromus,’ to the European habitat is added “ Httam in Islandia et 
in Terra Nova Americ Borealis.” But it does not appear that 
Mr. Bentham had ever seen an American specimen. He also over- 
looked the fact (to which Dr. Seemann has recently called attention) 
that Gisecke, in Brewster’s ‘ Encyclopedia,’ records it as a native of 
Greenland. No mention of it is made by Dr. Lang, in his enumeration 
of the known plants of Greenland, appended to Rink’s ‘ Geographical 
and Statistical Account of Greenland,’ published in 1857 ; from which 
we may infer that the plant is perhaps as rare and local in Greenland 
as in Newfoundland, or even in Massachusetts. In September, 1861, 
Dr. Gray announced the unexpected discovery, by Mr. Jackson Dawson, 
