Letters to Ebenezer Hancock from his mother, Mary Perkins, and his stepfather, Daniel Perkins, 1758 June 27 and 1758 November 16

These two letters were written to Ebenezer Hancock while he was an undergraduate at Harvard College. His stepfather, Daniel Perkins, wrote on June 27, 1758 and his mother, Mary Perkins, wrote on November 16, 1758. Both letters were sent from Bridgewater, Massachusetts, where the Perkins lived. The letters contain general greetings and wishes for Hancock's well being, as well as parental advice regarding his behavior and comportment.

Letter from George Richards Minot to Daniel Kilham, 1777 December 1

Three-page handwritten letter from Harvard undergraduate George Richards Minot to his friend and Harvard graduate Daniel Kilham, dated December 1, 1777. The letter describes the discipline inflicted upon Minot and seven of his classmates by the Harvard government following a “Thanksgiving frolic,” and the retributions carried out by the students against a Tutor who recommended harsh measures for the accused students. The Early Faculty minutes for 1777 (UAIII 5.5, Volume 4, pages 75-76) describes the students’ crime as “making riotous & tumultuous noises in the Hall…committed in Presence of a number foreigners, & and on a day appointed by Authority for public Thanksgiving.”

Account book of Daniel Brigham, 1781-1798 (inclusive)

Account book maintained by Dr. Daniel Brigham (1760-1830) for services provided to approximately 180 patients, treated primarily in Northborough, Westborough, and Marlborough, Massachusetts, and surrounding towns between 1781 and 1798. The ledger details the charges for his visits to patients and medicines he prescribed. Common charges included one shilling, four pence for Brigham to visit and administer an emetic or cathartic to a patient. A visit and bloodletting by Brigham cost one patient two shillings, eight pence. He charged six shillings to amputate a toe, and eight pence to extract a tooth. Includes an index to patient names. The ledger also records household and miscellaneous expenses of Brigham.

Doctor Daniel Brigham's Book, 1789-1810 (inclusive)

Ledger maintained by Dr. Daniel Brigham (1760-1837) containing financial accounts for medical patients treated primarily in Northborough, Westborough, and Marlborough, Massachusetts from 1789 to 1837. The ledger details the charges for medical services and the corresponding payments, often made by payment-in-kind. Common charges included a shilling for a visit and administration of cathartics, emetics, or anodynes. Extraction of a tooth cost eight pence, and Brigham charged one woman nine shillings for delivering her son. A number of entries are obscured by pasted-in newspaper articles.

Benchmarking analogue models of brittle thrust wedges

We performed a quantitative comparison of brittle thrust wedge experiments to evaluate the variability among analogue models and to appraise the reproducibility and limits of model interpretation. Fifteen analogue modeling laboratories participated in this benchmark initiative. Each laboratory received a shipment of the same type of quartz and corundum sand and all laboratories adhered to a stringent model building protocol and used the same type of foil to cover base and sidewalls of the sandbox. Sieve structure, sifting height, filling rate, and details on off-scraping of excess sand followed prescribed procedures. Our analogue benchmark shows that even for simple plane-strain experiments with prescribed stringent model construction techniques, quantitative model results show variability, most notably for surface slope, thrust spacing and number of forward and backthrusts. One of the sources of the variability in model results is related to slight variations in how sand is deposited in the sandbox. Small changes in sifting height, sifting rate, and scraping will result in slightly heterogeneous material bulk densities, which will affect the mechanical properties of the sand, and will result in lateral and vertical differences in peak and boundary friction angles, as well as cohesion values once the model is constructed. Initial variations in basal friction are inferred to play the most important role in causing model variability. Our comparison shows that the human factor plays a decisive role, and even when one modeler repeats the same experiment, quantitative model results still show variability. Our observations highlight the limits of up-scaling quantitative analogue model results to nature or for making comparisons with numerical models. The frictional behavior of sand is highly sensitive to small variations in material state or experimental set-up, and hence, it will remain difficult to scale quantitative results such as number of thrusts, thrust spacing, and pop-up width from model to nature.

Atmospheric histories and global emissions of halons H-1211 (CBrClF 2 ), H-1301 (CBrF 3 ), and H-2402 (CBrF 2 CBrF 2 )

We report ground-based atmospheric measurements and emission estimates for the halons H-1211 (CBrClF₂), H-1301 (CBrF₃), and H-2402 (CBrF₂CBrF₂) from the AGAGE (Advanced Global Atmospheric Gases Experiment) and the National Oceanic and Atmospheric Administration global networks. We also include results from archived air samples in canisters and from polar firn in both hemispheres, thereby deriving an atmospheric record of nearly nine decades (1930s to present). All three halons were absent from the atmosphere until ~1970, when their atmospheric burdens started to increase rapidly. In recent years H-1211 and H-2402 mole fractions have been declining, but H-1301 has continued to grow. High-frequency observations show continuing emissions of H-1211 and H-1301 near most AGAGE sites. For H-2402 the only emissions detected were derived from the region surrounding the Sea of Japan/East Sea. Based on our observations, we derive global emissions using two different inversion approaches. Emissions for H-1211 declined from a peak of 11 kt yr⁻¹ (late 1990s) to 3.9 kt yr⁻¹ at the end of our record (mean of 2013–2015), for H-1301 from 5.4 kt yr⁻¹ (late 1980s) to 1.6 kt yr⁻¹, and for H-2402 from 1.8 kt yr⁻¹ (late 1980s) to 0.38 kt yr⁻¹. Yearly summed halon emissions have decreased substantially; nevertheless, since 2000 they have accounted for ~30% of the emissions of all major anthropogenic ozone depletion substances, when weighted by ozone depletion potentials.

Poesias de Daniel Bayona Posada.

"Prologo" by Juan de Dios Bravo.