Literal Comprehension

The following passage is adapted from an article on early atmospheric aviation.

On the morning of May 27, 1931, Swiss physicist Auguste Piccard and his assistant Paul Kipfer stepped inside a spherical, airtight aluminum gondola attached to a massive hydrogen-filled balloon named FNRS-1. Launching from Augsburg, Germany, their primary objective was to reach the stratosphere to measure cosmic rays.

Shortly after ascent, a critical mechanical failure occurred: a pressure valve malfunctioned, causing a sudden drop in cabin pressure. Working quickly in the cramped sphere, Kipfer sealed the leaking valve joint using a rudimentary compound of petroleum jelly and oakum fiber. Once the leak was secured, the balloon continued its climb into the upper atmosphere.

At 3:57 PM, the FNRS-1 reached a peak altitude of 15,781 meters (51,775 feet), making Piccard and Kipfer the first human beings to enter the stratosphere. However, a new crisis emerged within the cabin. The motorized mechanism designed to slowly rotate the gondola—intended to regulate internal temperature by turning the heat-reflecting silver side toward the Sun—failed completely. Suspended with the dark-painted side facing the Sun constantly, internal cabin temperatures soared past 106°F (41°C).

Desperately short of liquid oxygen and suffering from severe heat exhaustion, the two aeronauts spent several hours drifting across the Alps. Finally, as cold air aloft caused the hydrogen gas to contract, the balloon began a gradual descent. At 8:50 PM, the gondola touched down safely on the snowpacks of the Gurgler glacier near Obergurgl, Austria, concluding a historic seventeen-hour voyage.

Based on the passage, place the following explicitly stated events from Auguste Piccard's flight in the chronological order in which they occurred from first to last.

Read the following passage carefully:

Before Dr. Maya Lin embarked on her 2018 expedition to the Antarctic Peninsula to sample subglacial meltwater, she spent two years synthesizing satellite telemetry collected during the 2012 Polar Sentinel mission. Her interest in subglacial hydrology had actually been sparked years prior, when she read Dr. Alistair Vance’s 2004 seminal paper on sub-ice lakes while completing her undergraduate thesis in 2007. Upon arriving at McMurdo Station in early 2018, Lin discovered that her primary drill rig had suffered severe mechanical failure during transit—a setback reminiscent of her failed 2015 pilot study in Greenland, where extreme weather destroyed her temperature sensors. Rather than aborting the 2018 mission, Lin pivoted to deploying autonomous thermal probes, a technique she had perfected while consulting for a deep-sea geothermal project in 2016. By late 2019, after analyzing the data recovered by the thermal probes, Lin published her landmark study proving the existence of interconnected subglacial rivers.

Based on the passage, in what chronological order did the following events occur from earliest to latest?

The following passage is adapted from an article on mid-twentieth-century oceanography and plate tectonics:

In the summer of 1947, oceanographer Maurice Ewing led an expedition aboard the research vessel Atlantis to map the Mid-Atlantic Ridge. At the time, prevailing geological theory held that the ocean floor consisted of a thick layer of continental granite covered by miles of accumulated sediment. Ewing utilized seismic refraction measurements, sending acoustic shockwaves from small explosive detonations down to the sea floor and recording the echo timings with hydrophones.

The results shattered long-held assumptions. Ewing discovered that the oceanic crust was composed entirely of dense basalt, not granite. Furthermore, the sediment layer measured less than 1,000 feet thick, a fraction of the 12,000-foot thickness predicted by conventional models of an ancient, static ocean floor. This thin sediment layer indicated that the Atlantic floor was geologically young, providing crucial empirical evidence that eventually supported the theory of seafloor spreading.

According to the passage, what specific equipment did Ewing use aboard the Atlantis to record the echoes of the acoustic shockwaves?

Passage:
Passive solar heating and active solar heating both capture solar radiation to provide warmth to interior spaces, but they employ distinct physical mechanisms. Passive solar systems rely entirely on the architectural elements of a building—such as south-facing glass windows and high-density masonry floors—to collect and distribute heat naturally without mechanical intervention. In contrast, active solar systems require external mechanical or electrical devices, including liquid collectors, pumps, and circulating fans, to absorb thermal energy and transport it throughout the structure.

Based on the passage, what is one explicit difference between passive solar heating and active solar heating?

The following passage is adapted from an essay on the history of experimental low-temperature physics:

In April 1911, Dutch physicist Heike Kamerlingh Onnes and his research team at Leiden University conducted groundbreaking electrical resistance experiments on metals at cryogenic temperatures. Three years earlier, in 1908, Onnes had become the first scientist to liquefy helium, achieving a temperature of $4.2\text{ K}$ ($-268.95^\circ\text{C}$). This breakthrough allowed his team to systematically investigate how electrical resistance behaved in conductors near absolute zero.

Initial theoretical opinions regarding electrical conductivity at ultra-low temperatures were sharply divided among early twentieth-century physicists. Lord Kelvin had hypothesized that as temperature decreased toward absolute zero, conduction electrons would freeze in place, causing electrical resistance to increase toward infinity. Conversely, Onnes originally conjectured that electrical resistance would steadily diminish and smoothly approach zero as thermal motion ceased.

To test these competing hypotheses, Onnes and his assistant Gilles Holst constructed a closed glass capillary tube containing purified mercury. Mercury was selected because it could be repeatedly distilled to eliminate chemical impurities that might distort resistance measurements. The capillary tube was submerged in a double-walled bath of liquid helium inside a vacuum-insulated cryostat. As the team systematically reduced the vapor pressure over the liquid helium bath to lower the temperature, Holst monitored the potential difference across the mercury capillary using a sensitive Wheatstone bridge.

At a temperature of approximately $4.20\text{ K}$, the electrical resistance of the mercury sample did not drop gradually as Onnes had anticipated. Instead, within a temperature interval of less than $0.01\text{ K}$, the resistance plummeted abruptly from $0.11\text{ ohms}$ to less than one-hundred-thousandth of an ohm ($10^{-5}\text{ ohms}$), falling below the detection threshold of their instruments. Initially suspecting a short circuit in the wiring connections outside the cryostat, Holst and Onnes spent hours inspecting the external terminal leads before confirming that the mercury had entered a novel state of zero resistance, which Onnes subsequently named 'superconductivity' in 1912.

According to the passage, why did Kamerlingh Onnes and his team specifically choose mercury for their low-temperature electrical resistance experiments?

Passage Excerpt:
Glaciers move across landscapes through two primary mechanisms: basal sliding and internal deformation. Basal sliding occurs when liquid water under immense pressure acts as a lubricant beneath the glacier, allowing the entire ice mass to melt slightly at its base and slide over bedrock. In contrast, internal deformation occurs when individual ice crystals within the glacier slip past one another under the weight of overlying ice without requiring subglacial liquid water. While basal sliding dominates in warmer temperate glaciers where basal ice reaches the melting point, internal deformation is the principal movement mechanism in cold polar glaciers, where the ice remains frozen solid to the bedrock below.

Based on the passage, what is one explicitly stated difference between basal sliding and internal deformation?

Read the following passage:

In 1903, botanist Clara Hallowell began her research into native fern species in Maine. After publishing her preliminary survey in 1906, she traveled to Europe in 1908 to consult with herbarium curators. Upon returning home in 1910, Hallowell established the state's first protected botanical reserve before releasing her definitive textbook on regional flora in 1914.

Based on the passage, which of the following events occurred immediately after Clara Hallowell returned home in 1910?

Read the following passage and answer the question below.

In the spring of 1904, horologist Julien Mercier published his comprehensive manual on restoring marine chronometers, a work he began writing only after completing the delicate restoration of the HMS Resolution’s clock. Two years prior to that restoration, however, Mercier had discovered the clock’s missing brass escapement wheel in a forgotten crate at the Portsmouth naval dockyards. He did not immediately clean or reassemble the piece; instead, he spent eight months analyzing the alloy’s metallurgical composition to ensure compatibility with modern preservation solvents. Only when those tests concluded in late 1901 did Mercier return to his bench to rebuild the gear train. Interestingly, before he ever set foot in Portsmouth or laid eyes on the escapement wheel, Mercier had served an intensive six-year apprenticeship under master watchmaker Gabriel Laurent in Paris, during which he first conceptualized his non-invasive solvent technique.

According to the passage, which of the following events occurred EARLIEST in Julien Mercier's career?

The following passage is adapted from an essay on the history of architectural acoustics:

In the autumn of 1895, Harvard University officials asked Wallace Clement Sabine, a thirty-eight-year-old assistant professor of physics, to solve a severe acoustical flaw in the lecture hall of the university's newly completed Fogg Art Museum. Speakers in the room found their words rendered unintelligible by an overwhelming echo that lingered for over five seconds. Armed with little more than a set of gemshorn organ pipes, a stopwatch, and his own sharp hearing, Sabine set out to quantify the behavior of sound within enclosed spaces.

Sabine hypothesized that the excessive duration of sound persistence—what he termed reverberation time—was directly related to the sound-absorbing capacity of the materials lining the room. To test this, he needed a standardized sound absorber. Sabine turned to the upholstered cushions in the auditorium of the nearby Sanders Theatre. Night after night, after campus activities concluded, Sabine and his assistants manually transported hundreds of cushions from Sanders Theatre into the Fogg lecture hall. By measuring the reverberation time after adding incremental lengths of cushion along the hall's hard pine benches, Sabine calculated the exact absorption coefficient of the cushion fabric and horsehair filling.

His meticulous experiments revealed that reverberation time was directly proportional to room volume and inversely proportional to total acoustic absorption. Sabine expressed this relationship in a concise mathematical formula, establishing architectural acoustics as a rigorous quantitative science. Impressed by his findings, the architectural firm McKim, Mead & White engaged Sabine in 1898 to serve as the acoustic consultant for the design of the new Boston Symphony Hall. Rejecting the prevailing fan-shaped auditorium trends of the era, Sabine recommended a traditional rectangular 'shoebox' layout with shallow balconies and heavy wall statues to diffuse sound. When Boston Symphony Hall opened on October 15, 1900, its acoustic clarity was hailed worldwide, cementing Sabine's empirical approach as the cornerstone of modern hall design.

Based on the passage, evaluate whether the following statement is True or False:
Wallace Clement Sabine borrowed upholstered cushions from Sanders Theatre to measure how absorbing materials affected reverberation time in the Fogg Art Museum's lecture hall.

Read the following passage carefully:

Architect Marcus Vance designed the new city library over a multi-year period. In 2012, he submitted his initial architectural blueprints to the city council for formal review. After receiving approval the following year in 2013, construction crews officially began laying the main foundation. Finally, in 2014, the building's signature glass dome was installed, marking the completion of the structural exterior.

Based on the explicit statements in the passage, arrange the following events in chronological order from earliest to latest.

Read the passage below and evaluate whether the statement that follows is True or False.

In October 1926, Russian botanist Nikolai Vavilov embarked on a five-month botanical survey across the mountainous regions of Abyssinia (modern-day Ethiopia). Supported by the All-Union Institute of Applied Botany, Vavilov sought to identify primary centers of origin for cultivated crops. Unlike earlier collectors who prioritized yield potential, Vavilov systematically documented indigenous landraces, recording morphological traits and microclimatic conditions across varying altitudes.

During his ascent into the central highlands between 1,800 and 2,400 meters, Vavilov gathered over 2,000 distinct seed samples, primarily focusing on cereal grains such as durum wheat and teff (Eragrostis tef). He observed that local farmers preserved distinct landraces within isolated mountain valleys, preventing cross-pollination through geographic barriers rather than intentional selective breeding. Crucially, Vavilov recorded that while coffee (Coffea arabica) grew wild in the southwestern rainforests of Kaffa, cultivated varieties of teff exhibited far greater genetic diversity across the northern plateau.

In his field journals, Vavilov noted a striking anomaly regarding bread wheat (Triticum aestivum). Although bread wheat was widely grown throughout Europe and Southwest Asia, the Abyssinian samples displayed unique dominant genetic traits, specifically awnless spikes and dark purple caryopses, which were virtually absent in Mediterranean specimens. However, Vavilov emphasized that Abyssinia was a secondary, rather than primary, center of origin for bread wheat, because wild ancestral ancestors of Triticum aestivum were entirely absent from the local flora. Conversely, because wild relatives of teff were abundant alongside cultivated landraces, he designated the region as the primary center of origin for teff.

Upon completing his expedition in March 1927, Vavilov transferred the seed collection to Leningrad for cold-storage preservation and cytogenetic analysis. His findings challenged the prevailing assumption that high crop diversity was merely a product of ancient trade routes, demonstrating instead that geographic isolation and environmental heterogeneity were the primary drivers of localized genetic variation.

Statement: According to the passage, Vavilov designated Abyssinia as a secondary center of origin for bread wheat specifically because wild ancestral relatives of Triticum aestivum were completely absent from the region's local flora.

The following passage is adapted from an article on early Aegean archaeology and epigraphy:

On April 4, 1939, a joint Hellenic-American archaeological expedition led by Carl Blegen of the University of Cincinnati initiated test excavations on the hilltop of Epano Englianos near modern Pylos, Greece. Blegen aimed to locate the Mycenaean-era palace mentioned in Homer’s Iliad as the seat of King Nestor. On the very first morning of trenching, workers uncovered a cache of sun-baked clay tablets inscribed with a script known as Linear B. Prior to this discovery, Linear B had been documented exclusively on the island of Crete, most notably by Sir Arthur Evans at Knossos during his excavations beginning in 1900. Evans had maintained that Linear B was a non-Greek script unique to Minoan civilization and restricted entirely to Cretan administration. The unexpected presence of inscribed tablets on the Greek mainland immediately challenged Evans's insular narrative.

Among the items cataloged during that initial 1939 season was a distinctive rectangular tablet designated by Blegen's team as Tablet Ta-641. Unlike the vast majority of administrative records found at Epano Englianos—which recorded inventory figures for agricultural goods such as olive oil, grain, and flax—Tablet Ta-641 contained detailed depictions of tripods, three-legged cauldrons, and two-handled drinking vessels. Accompanying these pictogram drawings were ideograms alongside syllabic Linear B characters. The tablet specifically recorded three tripods of Cretan workmanship, two large bronze cauldrons with decorated rims, and four gold-inlaid goblets used for ceremonial libations. Crucially, Blegen carefully photographed and preserved the tablet before burying the excavated trenches to protect the site upon the outbreak of World War II later that autumn.

When archaeological operations resumed in 1952 following the war, British architect and self-taught linguist Michael Ventris was analyzing high-resolution photographs of Tablet Ta-641 provided by Blegen. Ventris had been working on a grid system developed by American classicist Alice Kober, who had previously identified inflectional patterns in Linear B signs indicating grammatical endings. Using Kober's grid and cross-referencing the ideograms on Tablet Ta-641 with their accompanying syllabic text, Ventris observed that the syllabic word printed alongside the drawing of a three-legged cauldron was ti-ri-po-de, extraordinarily close to the Ancient Greek word tripodes. Furthermore, the text alongside a two-handled vessel read di-pa-we, corresponding to the archaic Greek dipas. On June 18, 1952, Ventris formally announced during a BBC radio broadcast that Linear B was not an undeciphered Minoan tongue, but rather the earliest written form of the Greek language, now known as Mycenaean Greek.

Although Sir Arthur Evans had passed away in 1941 without witnessing the decipherment, his long-standing hypothesis that mainland Greece was merely a provincial dependency of Minoan Crete was decisively disproved by the Pylos tablets. The literal statements recorded on Tablet Ta-641 demonstrated that the Mycenaeans of mainland Greece maintained sophisticated administrative control, native Greek literacy, and complex ritual practices fully independent of Cretan oversight as early as the fourteenth century BCE.

According to the passage, Tablet Ta-641 differed explicitly from the majority of administrative clay tablets discovered at Epano Englianos in 1939 because it cataloged information regarding which of the following?

Read the following passage carefully:

Before Evelyn Briggs published her catalog on 19th-century textiles in 1952, she spent three years organizing the museum's uncatalogued private collections. Her research formally began in 1947 after she received a research grant from the Historical Society. However, it was not until 1949—the year prior to her appointment as head curator—that she uncovered the rare silk samples in the museum basement.

Based on the passage, which of the following events occurred FIRST in Evelyn Briggs's career timeline?

Read the following passage carefully:

In June 1977, oceanographers aboard the research vessel Lulu prepared the submersible Alvin for a deep dive near the Galápagos Rift. Before the crew boarded the vessel, engineers conducted a thorough pressure-test of the hull at sunrise. Once Alvin was lowered into the Pacific waters, the pilot engaged the flood tanks to begin the two-hour descent to the ocean floor. Near the mid-point of the dive, the team activated the external halogen lights to navigate the pitch-black midwater zone. Finally, upon reaching the seabed, the scientists recorded water temperature anomalies that led directly to the discovery of hydrothermal vents.

Based on the passage, in what chronological order did these events occur during the expedition?

The following passage is adapted from an essay on the history of natural history and botanical illustration:

In June 1699, fifty-two-year-old German-born naturalist Maria Sibylla Merian took an unprecedented step for an independent woman of her era: she sold her estate in Amsterdam to self-fund a scientific expedition to South America. Accompanied by her youngest daughter, Dorothea, Merian boarded a ship bound for Paramaribo, the capital of Suriname. At the time, naturalists rarely observed insects in their wild habitats, relying instead on preserved, dried specimens shipped to European cabinets of curiosity. Merian, however, was determined to study living organisms directly, documenting their full life cycles and ecological relationships.

Upon arriving in Suriname later that summer, Merian began conducting intense field study in the dense rainforests surrounding Paramaribo. Over the course of nearly two years, she collected, bred, and painted dozens of native insect species alongside the host plants upon which they fed. Her work shattered contemporary assumptions regarding spontaneous generation by meticulously capturing the metamorphosis of caterpillars into moths and butterflies. However, in the summer of 1701, an unexpected illness—likely malaria—compelled Merian to prematurely terminate her field research and return to Europe to recover.

Back in Amsterdam, Merian spent three years preparing her field sketches and notes for publication. Refusing to rely on third-party publishers who might compromise the scientific fidelity of her copperplate engravings, she personally oversaw every aspect of production. In 1705, she issued her monumental work, *Metamorphosis Insectorum Surinamensium* (*The Metamorphosis of the Insects of Suriname*), financed entirely through a private subscription model she organized herself. The publication set a new standard for scientific illustration by depicting insects together with the specific plant species they inhabited.

Based on the passage, place the following biographical events involving Maria Sibylla Merian in the correct chronological order as they explicitly occurred.

Passage:
Botanists categorize plant root systems into two main structures: taproot systems and fibrous root systems. A taproot system features one single, prominent main root that grows deep vertically into the soil, with smaller lateral roots branching off it. This deep penetration allows taproot plants, such as dandelions and carrots, to reach deep groundwater reserves during dry periods. In contrast, a fibrous root system consists of a dense network of numerous thin roots of roughly equal size that spread horizontally near the soil surface. Unlike taproot systems, fibrous root systems, commonly found in grasses and wheat, prevent topsoil erosion by anchoring the upper layer of soil securely.

According to the passage, how does a taproot system explicitly differ from a fibrous root system in its physical structure?

In the early months of 1922, oceanographer Dr. Corinne Vance embarked on a series of deep-water expeditions off the coast of the Aleutian Islands. Unlike her contemporaries who relied on theoretical models of oceanic currents, Vance insisted on gathering empirical hydrographic data firsthand under extreme maritime conditions. Colleagues frequently described her as remarkably unflappable during sudden Arctic gales, noting that while others retreated below deck to manage seasickness, she remained at the railing recording water temperature and salinity readings. Vance’s calm demeanor in high-stress environments enabled her team to assemble the first comprehensive data set on North Pacific abyssal currents. Though her written reports were famously terse and devoid of narrative flair, the sheer accuracy of her measurements earned her widespread recognition among international hydrographic societies.

Based on the passage, which trait was directly attributed to Vance by her colleagues?

The following passage is adapted from an essay on mid-twentieth-century oceanographic history:

In early 1977, an oceanographic research team launched an expedition to investigate thermal anomalies along the Galápagos Rift, an active seafloor spreading center in the eastern Pacific Ocean. Because deep-sea submersibles operated under strict battery limitations and brief dive windows, researchers relied on preliminary surveying tools before deploying crewed vessels. On February 15, the surface support ship towed the unmanned, camera-equipped sled known as ANGUS (Automated Nautical Geophysical Underwater System) just meters above the basaltic seabed. During this run, ANGUS recorded a localized temperature increase of $0.1^\circ\text{C}$ while simultaneously photographing clusters of giant white clam shells resting on the ocean floor.

Analyzed immediately by onboard geophysicists, the thermistor data and black-and-white photographs allowed the team to pinpoint the precise coordinates of the anomaly, which they designated as 'Clambake I.' Two days later, on February 17, geologists Jack Corliss and Tjeerd van Andel boarded the three-person submersible *Alvin* to execute Dive 713. Descending to a depth of roughly $2{}500\text{ meters}$, the pilots navigated directly toward the coordinates mapped by ANGUS. Upon reaching the rift valley floor, the observers witnessed clear, warm water shimmering as it emanated from narrow fractures in the volcanic basalt. This direct observation provided the first conclusive proof of active hydrothermal venting on the ocean floor.

Based on the explicit details provided in the passage, in what chronological order did the events of the Galápagos Rift expedition occur?

For over two decades, volcanologist Dr. Beatriz Morales monitored active lava tubes along Iceland's Southern Peninsula with an unyielding methodological caution that her graduate students initially found perplexing. While visiting researchers frequently rushed to install experimental seismic sensors directly onto fragile basalt shelves, Dr. Morales insisted on conducting exhaustive structural assessments before allowing any heavy equipment near active fissure vents. She maintained a strict protocol of recording atmospheric pressure and gas composition manually every three hours, refusing to rely solely on automated telemetry systems. Colleagues often remarked that this persistent reliance on manual verification stemmed not from a distrust of modern technology, but from her deep conviction that direct observation fostered a unique intuitive grasp of volcanic behavior.

According to the passage, which of the following best describes Dr. Beatriz Morales's explicitly stated trait when conducting fieldwork?

The following passage is adapted from an article on early twentieth-century scientific expeditions:

In March 1927, Russian mineralogist Leonid Kulik set out on the first systematic field expedition to investigate the catastrophic explosion that had devastated central Siberia nearly nineteen years earlier. On June 30, 1908, a mysterious atmospheric detonation over the Podkamennaya Tunguska River basin had flattened thousands of square kilometers of dense taiga. Yet, owing to the extreme remoteness of the region and the political turmoil of the Russian Civil War, no physical survey of the site had been undertaken. Having secured a modest allocation of 1,500 rubles from the Soviet Academy of Sciences following his 1921 preliminary survey of Siberian meteorite reports, Kulik established an operational base at the isolated Vanavara trading post. From Vanavara, Kulik and his team traveled northward across frozen bogs and dense forests using reindeer sleds provided by local Evenki hunters.

Upon reaching the inner perimeter of the devastation near the Makirta River in mid-April, Kulik made an unexpected observation regarding the structural condition of the forest. Scientists had anticipated that a massive surface impact would have uprooted trees uniformly in a radial direction from the central point. However, as the expedition traversed the outer region—where millions of larch and pine trees lay prone on the ground, pointing symmetrically outward—they eventually arrived at a broad depression known locally as the 'Great Cauldron.' Here, at the precise center of the blast area, the pattern of forest damage altered dramatically. Instead of being uprooted, the trees at the immediate epicenter remained standing fully erect. Their branches, twigs, and bark had been completely stripped away by intense heat and shockwaves, leaving thousands of bare, scorched trunks upright like a forest of stark telegraph poles across a twenty-kilometer radius.

Kulik recognized that this peculiar configuration of standing, branchless timber provided vital physical evidence regarding the nature of the event. The vertical alignment of the trunks indicated that the explosive shockwave had struck the ground from directly above, propagating downward at a perpendicular angle rather than laterally across the terrain. This observation led Kulik to hypothesize that the object had not struck the Earth's surface as a solid mass, but had instead detonated violently in the upper atmosphere.

Despite this breakthrough, Kulik remained determined to locate solid physical remnants of the object. He focused his search on several marshy depressions within the epicenter, most notably a peat bog dubbed the Suslov funnel. Kulik suspected that these depressions represented impact craters created by a fragmented iron meteorite. Armed with hand-operated drills and spades, the expedition spent months excavating the frozen mud of the Suslov funnel during the summer thaw of 1927. However, the labor yielded no nickel-iron meteoritic fragments, nor did it reveal any underlying impact crater structure. Subsequent analysis confirmed that the Suslov funnel was merely a natural thermokarst formation produced by the melting of permafrost. Although Kulik returned to Moscow without the physical extraterrestrial specimens he sought, his meticulous mapping of the epicenter's erect, scorched timber established the foundational scientific understanding of high-altitude atmospheric airbursts.

Based on the passage, what did Leonid Kulik observe regarding the condition of the trees situated at the immediate epicenter of the blast during his 1927 expedition?