{"display_title": "Rare air, snow blindness, and remarkable human endurance", "components": [{"component_name": "paragraph", "paragraph": "The material discusses human physiology mainly through the effects of extreme altitude, intense light, unusual environments, and strenuous exertion. It presents these observations as explanations of how the senses and body respond, although some nineteenth-century interpretations are now described in the text as uncertain or disputed."}, {"component_name": "heading", "heading": "Altitude and breathing", "level": 2}, {"component_name": "list", "ordered": false, "list": ["At high elevations in the Himalayas, the air becomes increasingly rarefied, producing difficulty breathing. The text says travellers may also be oppressed by heat, piercing winds, and vertigo while looking down steep precipices.", "In the Andes, the altitude illness called veta was said to begin at about 12,600 feet. Its listed symptoms are vertigo, dimness of sight and hearing, headache, nausea, and bleeding from the eyes, nose, and lips; severe cases could include fainting and spitting blood.", "A related condition called surumpe was attributed to the sudden reflection of sunlight from snow. The text describes severe eye inflammation, burning pain, swollen and bleeding eyelids, and sometimes delirium; it compares the sensation to having cayenne pepper rubbed into the eyes. Creole travellers reportedly used green spectacles and veils for protection.", "Humboldt reportedly stopped his attempted ascent of Chimborazo when blood appeared beneath his fingernails and eyelids, which the book attributes to the rarity of the air.", "On Mont Blanc, climbers became exhausted by very small exertions, experienced breathlessness and chest oppression, had excessive thirst, and lost their appetite. One account says that a climber could take only fifteen or sixteen steps before needing to stop for breath, while descending to lower altitude quickly restored strength and appetite."]}, {"component_name": "heading", "heading": "Sight, touch, hearing, and perception", "level": 2}, {"component_name": "list", "ordered": false, "list": ["The text repeatedly links intense visual stimuli with bodily reactions. On descending Mont Blanc, the glare reflected from sunlit precipices was said to be so dazzling that it could make travellers giddy.", "A traveller in the exceptionally clear water of Lake Superior reported that looking down at rocks more than six fathoms below made his head swim and his eyes unable to keep viewing the dazzling scene.", "The book describes people being deceived by mirages: French soldiers in Egypt reportedly saw what appeared to be a lake that seemed to retreat as they approached. It explains the effect as light being bent by layers of air with different temperatures and densities.", "The supposed 'spectre of the Brocken' is explained as a person's image, magnified and distorted when projected onto an opposite cloud under particular atmospheric conditions.", "The book also notes that people can experience fear and bodily alarm in response to extreme surroundings: travellers crossing Himalayan precipices are described as terrified, and miners during the Lisbon earthquake reported moving rocks, grinding sounds, and rumbling 'like groans' from underground."]}, {"component_name": "heading", "heading": "Adaptations and unusual bodily abilities in people", "level": 2}, {"component_name": "list", "ordered": false, "list": ["The Guachos of the South American Pampas are described as spending much of their lives on horseback and throwing a lasso accurately while galloping. The text attributes this skill to years of practice and says that even children practise by lassoing cats and entangling dogs.", "Shepherds on the Landes of Bordeaux are said to walk and work on stilts three or four feet above the ground. The stated reasons are to see widely scattered sheep and to cross marshy ground quickly; the accompanying stick acts as a third leg for support.", "The text gives an example of extraordinary human endurance after a mountain collapse: a shepherd was reportedly buried beneath rocks for many days, surviving on cheese and a small stream of water before finding an opening. When brought into daylight, his eyes initially could not tolerate the light.", "At very high elevations, the book records that cats could not survive. Attempts to keep them at about 13,000 feet reportedly ended after a few days in convulsions, which the text connects with the same altitude illness affecting people."]}, {"component_name": "heading", "heading": "Other physiological conditions", "level": 2}, {"component_name": "list", "ordered": false, "list": ["The book discusses goitre and cretinism in Alpine valleys. It reports enlarged throats, rickets, bodily deformity, and mental impairment among the people called Cretins, while noting that modern writers disputed the older claim that melted glacier water itself was the cause and instead proposed unhealthy, stagnant air in sheltered valleys.", "It describes the physical effects of a desert wind called the Zonda: it could blister the skin of the face and hands, while intense heat and reflected light made it difficult to keep one's sight fixed on the route.", "The account of the Puna says that intense cold can kill travellers and rapidly dry bodies, while the contraction of facial muscles after death can give corpses an appearance resembling laughter."]}]}

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