The Ancient Mariner and the transit of Venus.
The achievements of William Wales FRS - astronomer, classical scholar, demographer, editor, mathematician, meteorologist and humane teacher - have been overshadowed by the fame of Cook's extraordinary voyages, and overlooked as a significant influence on Samuel Taylor Coleridge's early development. The Royal Society sent Wales to Hudson Bay, Canada, and James Cook to Tahiti, both to observe the 1769 transit of Venus as part of an international project to calculate solar parallax, and hence the distance to the Sun. Wales later taught mathematics and navigation science at Christ's Hospital School to a precocious Coleridge, whose creative mind translated tales of polar adventures into memorable poetry.
Icy hell – a history of ice and snow – part 2
Snow is a favourite romantic theme in Western literature, from Andersen’s fairytale Snow Queen to Joyce’s ‘The Dead’ in Dubliners and Dickens’ A Christmas Carol. There are many references to snow in Japanese literature, too, in which snow is one of the three important subjects of poetry: setsugekka, literally snow, moon, and flowers.1 The most famous instance is almost undoubtedly Kawabata Yasunari’s Yukiguni (Snow Country), for which he won the Nobel Prize, whilst many other authors in Japan have written romantic tales with pure and evanescent snow in the background, from Tanizaki Jun’ichiro’s Sasame-yuki (Gentle Snow; titled The Makioka Sisters in translation) to Miyazawa Kenji’s Yuki-watari (Snow Crossing). Both in East and West snow inspires beautiful and poetic images, but once the subject turns to ice, romance disappears and negative images abound. On either side of the globe ice is associated with death and destruction; stories of an icy hell in Dante’s Inferno or of icy wastelands through which Coleridge’s Ancient Mariner and the monster of Mary Shelley’s Frankenstein travel, are no less freezing than those of people with a heart of ice in Hagiwara Sakutaro’s Hyoto (Island of Ice) and Miura Ayako’s Hyoten (Freezing Point; Box 1). In the field of science, ice is the general term for solid water and snow is the particular form ice takes when it precipitates from water vapour as the masses of dendritic crystals called snowflakes. Snow lying on the ground either melts or else compacts and densifies, forming firn and eventually bulk ice (see, e.g., Bartels-Rausch et al., 2012). Hail is formed of rain, congealed into ice: and snow of the same humour grown together, but not so hard, wrote Pliny (ca. 77 CE). Pliny, Seneca, and Augustine of Hippo thought crystals to be hardened ice; nothing else, but ice or snow concreted, and by duration of time, congealed beyond liquidation (Browne, 1646). Following this tradition, Jerome translated qerah, the Hebrew word for ice, into the Latin crystallus in his commentary on Ezekiel. Thus, ice crystals came to be treated indiscriminately with rock crystals, symbolising order in a chaotic world, being alive although seemingly dead, standing in between matter and spirit, by subsequent authors from Swedenborg and Goethe down to Thoreau and Emerson (see Wilson, 2003). Even if there is no difference in its aqueous essence, however, the snowflake as it falls appears quite different from seemingly immobile ice. Contrary to the general Christian belief that hell is a fiery place, in Dante, the deepest hell is frozen, symbolic of cold betrayal; Brutus, Cassius, and Judas are the most damned and therefore are eternally bitten – or frostbitten – by Satan in icy Inferno. Beyond Christianity, the Nordic hell of Niflheim oe Hel (Utgard) was an icy one, from hence Ymir, the god of creation, was born (see Thorpe and Blackwell, 1906). And early scriptures of Buddhism such as Agama describe the eight spheres of icy hell ( ) alongside eight fiery hells ( ). Snow, on the other hand, often has paradisiacal religious associations since it falls from the sky, bringing a message down from heaven. A good example is Coleridge, whose snow-white albatross in the blizzard stands as a messenger from heaven in his Rime of the Ancient Mariner (1800; Box 2). Coleridge might not have been able to make this observation were he not living at the turn of the eighteenth to nineteenth centuries, which was a particularly cold time during the Little Ice Age. Coleridge’s
Grazing incidence optics for wide-field x-ray survey imaging: a comparison of optimization techniques
Discussions of optimizing wide-field x-ray optics, with field-of-view less-than 1.1 degree-squared, have been made previously in the literature. However, very little has been published about the optimization of wide-field x-ray optics with larger field-of-views, which technology could greatly enhanced x-ray surveys. We have been working on the design of a wide-field (3.1 degree-squared field-of-view), short focal length (190.5 cm), grazing incidence mirror shell set, with a desired rms image spot size of 15 arcsec. The baseline design consists of Wolter 1 type mirror shells with polynomial perturbations applied to the baseline design. The overall optimization technique is to efficiently optimize the polynomial coefficients that directly influence the angular resolution, without stepping through the entire multi-dimensional coefficient space. We have investigated optimization techniques such as the downhill simplex method, fractional factorial, and response surface (including Box- Behnken and central composite) design. We have also investigated the use of neural networks, such as backpropagation, general regression, and group method of data handling neural networks. We report our findings to date.