The Table Across the Basket

James Glaisher included a pair of scissors among his scientific instruments. The barometers, thermometers and other apparatus on his balloon table were attached with strings or mounted on screwed-down stands. When the basket approached the ground, the equipment had to be freed quickly and packed between cushions. The scissors were a precaution against breaking a laboratory on landing.

The table stretched across the basket, with Glaisher reading the instruments on one side and Henry Coxwell managing the balloon. Each arrangement had to serve two very different jobs. Glaisher needed small scales where he could see them, moving air around his thermometers and a surface on which to write. Coxwell needed access to ropes, ballast and the valve that let gas escape. High above England on 5 September 1862, with Glaisher unable to move, the table would stand between them.

Making weather vertical

Glaisher was a meteorologist and astronomer at the Royal Observatory, Greenwich. The atmosphere had interested him since his earlier surveying work on Irish mountains, where he could spend prolonged periods within cloud. At observatories, clouds were often the barrier that hid the stars. He wanted to know more about what was happening inside and above them.

The British Association’s Balloon Committee offered a way to carry instruments through those layers. Its programme chiefly concerned temperature and humidity at different heights. A collection of weather stations could describe conditions across the ground. A balloon could take an observer upwards, through air that a ground station never sampled.

Planning extended well beyond finding someone willing to ascend. In March 1862 the committee resolved that the instruments should be fitted into the basket before it left London. Ground observers were to be invited to make supporting observations; Lord Wrottesley was asked to measure the balloon’s altitude and direction from his observatory. A balloon seen from known positions could, in principle, have its height checked independently of the instruments aboard it. Glaisher later admitted that he never organised those ground checks to his satisfaction.

Coxwell supplied the practical expertise. An experienced balloonist, he built the large balloon used for the high ascents. He had to judge how much lift it possessed, how it behaved as the gas expanded, how much ballast remained and how far the wind was carrying it. Releasing sand made the load lighter and encouraged ascent. Releasing gas reduced lift. Neither operation provided a way to steer horizontally towards a chosen destination.

In his later memoir, Coxwell explained why speed could matter. A leisurely climb might carry them too close to the coast before the work was finished. The available time aloft had to include getting down somewhere suitable. He remembered being pleased with the unusually light gas supplied at Wolverhampton on 5 September. It gave him more lifting power than on the previous ascents.

Air through the apparatus

Glaisher’s instrument table was designed to answer several questions at once. Atmospheric pressure fell as they rose; barometer readings, combined with temperature, allowed height to be calculated. A thermometer gave the air temperature. Moisture required more elaborate work.

One pair of thermometers had a dry bulb and a moistened one. Evaporation cooled the wet bulb, and the difference between their readings helped establish humidity. Other instruments determined the dew point by cooling a surface until moisture condensed on it. The colder that surface had to become before dew appeared, the drier the surrounding air.

Sunlight could warm an instrument above the temperature of the air it was supposed to measure. Glaisher used polished silver shades to protect the bulbs. He also arranged thermometers in tubes through which air could be drawn by an aspirator, worked with bellows below the table. His apparatus required reading, pumping, watching for condensation and noting the time. It was a laboratory that depended on its operator’s eyes, hands and feet.

They left Wolverhampton at 1.03 p.m. The air temperature was 59°F, or 15°C. Ten minutes later they entered a thick cloud, where Glaisher found the air temperature and dew point equal: the air was saturated. On emerging into sunlight, he tried to photograph the cloudscape using sensitive dry plates supplied by Dr Hill Norris. The balloon was rising and revolving too quickly for the attempt to succeed.

The instruments continued to yield a vertical record. At two miles the temperature had fallen to freezing. At five miles, around eight kilometres, it was approximately −19°C. But useful observations were already being lost along the way. Glaisher rejected a stretch of wet-bulb readings because ice had not formed properly on the bulb. One dew-point instrument passed beyond its scale. With another, he could produce no visible dew even when he cooled it to −30°F, about −34°C.

At 1.34, Coxwell was panting for breath. Glaisher contrasted the pilot’s exertions with his own relative comfort at the table. Then the aspirator became troublesome, and the observer’s eyesight began to fail.

Two kinds of helplessness

Around 1.52, Glaisher still managed a dry-bulb reading of −5°F, about −21°C. Afterwards he could no longer distinguish the mercury in the wet-bulb thermometer, the watch hands or the instruments’ fine divisions. He asked Coxwell for help.

Coxwell had a competing emergency. The balloon’s continuing rotation had entangled the valve line, and he climbed into the ring above the basket to recover it. In his memoir, he explained that the suspension ropes had been made longer than usual. Reaching the ring therefore required an unusually long climb. He had already removed his thick gloves to handle the sandbags more easily.

Glaisher’s final observation came at 1.54. The barometer was still falling, indicating a height exceeding 29,000 feet—roughly 8.8 kilometres. He put an arm on the table and then discovered he could not use it. The other arm had lost its power too. He could shake his body for a time, but his legs would not obey him. His head fell towards one shoulder, then the other. He tried to speak and could not. His sight darkened before his consciousness finally went.

He described this as asphyxia. The thin air was depriving him of oxygen, while Coxwell was losing the use of his exposed hands. The two men’s essential abilities were disappearing separately: Glaisher could no longer observe; Coxwell could scarcely operate the means of descent.

Glaisher could not witness what saved him. After recovering, he recorded what Coxwell told him: the pilot had lowered himself from the ring using his arms, found Glaisher unresponsive and felt his own faculties beginning to fail. Unable to work the valve with his hands, Coxwell caught its cord with his teeth and dipped his head repeatedly until the balloon began descending.

Coxwell’s later account adds the obstruction in the basket. He tried to reach his companion, but the instrument table blocked the way, and with his disabled hands he could not pass beneath it. He kept working the valve line and watching their remaining ballast. As the balloon descended, its lower fabric slackened and the instrument needle moved. Glaisher still gave no answer.

When Glaisher began to recover, he heard Coxwell saying the words “temperature” and “observation”. Sight and movement returned. He took up his pencil. At 2.07 he recorded the barometer at 11.53 inches and the temperature at −2°F. The water supplying the wet-bulb thermometer had frozen solid.

Coxwell now needed help slowing the descent. They had to discard sand to check the fall, preserving enough to manage the rest of the journey. Glaisher treated Coxwell’s hands with brandy, then continued making observations.

Thirteen minutes without readings

There were thirteen minutes between Glaisher’s last observation on the ascent and his first on the descent. He estimated that he had been unconscious for about seven of them. The interval contained the top of the flight, but it contained no orderly sequence of summit measurements.

The often-repeated height of 36,000–37,000 feet, about eleven kilometres, came from reconstruction. Glaisher joined the known points using the time elapsed and estimates of their rates of ascent and descent. He also cited a minimum thermometer and Coxwell’s recollection of the aneroid barometer’s hand aligned with part of the rigging. He considered these indications mutually supporting. They did not amount to an instrument reading recorded at the summit.

The published profile makes the distinction visible: its highest curve is dashed. Much of the flight had produced timed pressure and temperature observations. At the point later celebrated as a seven-mile record, the record had broken off.

They landed at Cold Weston, near Ludlow. No conveyance was available, and the men had to walk seven or eight miles. Coxwell remembered reaching a hotel where they could get chops for dinner, then discovering that another guest had fish because he had caught and brought his own. Glaisher went to telegraph their whereabouts.

In Coxwell’s recollection, Glaisher wrote his report before and during breakfast the following morning.