Boston Dendrochronology Project

 

Selected sections from:

DEVELOPMENT OF STANDARD TREE-RING CHRONOLOGIES

FOR DATING HISTORIC STRUCTURES IN EASTERN MASSACHUSETTS

PHASE II

D H Miles1

M J Worthington1

Anne Andrus Grady2

MASSACHUSETTS HISTORICAL COMMISSION

SURVEY AND PLANNING GRANT

COMPLETION REPORT

Society for the Preservation of New England Antiquities

and

Oxford Dendrochronology Laboratory

Interim Report 2002/6

31st May 2002

 

Financial support for the SPNEA dendrochronology project in the form of matching funds for the MHC grant and funds to study additional buildings was provided by the Fairbanks House Association, the Winthrop Improvement and Historical Society and an anonymous donor. Their support is greatly appreciated.

The Development of Standard Tree-ring Chronologies for Dating Historic Structures in Eastern Massachusetts, Phase II, has been financed in part with federal funds from the National Park Service, U. S. Department of the Interior, through the Massachusetts Historical Commission, Secretary of the Commonwealth William Francis Galvin, Chairman. However, the contents and opinions do not necessarily reflect the views or policies of the Department of the Interior, or the Massachusetts Historical Commission.

 

I: ABSTRACT

In 2001-2002, the Society for the Preservation of New England Antiquities (SPNEA), assisted by a Survey and Planning grant from the Massachusetts Historical Commission (MHC), undertook Phase II of the project to develop standard tree-ring chronologies for oak in Eastern Massachusetts. In Phase I, completed in 2000-2001 and also supported by a grant from the MHC, dendrochronologists Dr Ed Cook and Paul Krusic from the Great Bay Tree-Ring Laboratory, Durham, New Hampshire, constructed a Boston Area Master Chronology (BOSTON01) covering the years 1513-1996. In addition to the six buildings dated as part of that first-year’s project which covered the period 1530-1785, the BOSTON01 chronology included a living tree chronology for Mt. Wachusett covering the period 1672-1997 and other unspecified sequences from the Saugus Ironworks House and possibly some of the 1975 material produced by Dr William Robinson (Krusic and Cook 2001). The goals of Phase II of the project were 1) to test the applicable geographic range of the BOSTON 01 chronology by studying buildings fifty or more miles from Boston, and 2) to increase the sample depth for the early part of the chronology before 1675, a period which was poorly represented in the BOSTON01 chronology.

During November and December of 2001, eleven sites were selected as part of the Phase II dendrochronological study. The technical aspects of the tree-ring dating including the sampling were carried out on behalf of SPNEA by Daniel Miles and Michael Worthington of the Oxford Dendrochronology Laboratory, England. Project planning, co-ordination, and research were carried out by Anne Grady for SPNEA. This included compiling a short list of the buildings to be sampled following a preliminary assessment, serving as liaison with the house holders and curators, and summarizing each building’s history and architecture. She also accompanied the dendrochronologists to the sites and provided transportation.

Some 156 samples from 122 timbers were taken from eleven sites throughout the greater Boston area. These included seven houses and three churches, with a fourth, the Chestnut Hill Meeting House in Millville, being assessed but not sampled due to lack of time. In addition, an archaeological timber from the Boston Mill Ditch archaeological dig was analysed. Buildings which dated include:

Fairbanks House, Dedham: 1640/41 and 1654/5

Gedney House, Salem: 1664/5 and 1705/6

Tuttle House, Ipswich: 1670/71 and 1672

Deane Winthrop House: 1674/5 and 1695/6

Coffin House, Newbury: 1677/8 and 1712/13

Cooper-Frost-Austin House, Cambridge: 1681

Pierce House, Dorchester: 1682/3 & 1711/12

Boston Mill Ditch: 1683/4

First Parish Church, Groton: 1753/4

Townsend United Methodist Church: 1769/70

Click here to see details of these dated buildings

Altogether sixteen phases of construction were sampled, of which fifteen dated, each producing at least one precise date. Only one building, the Prospect Street Friends’ Meeting House in Somerset, failed to date.

Funding for the Pierce House, Fairbanks House, Deane Winthrop House, Coffin House, Cooper-Frost-Austin House, and Groton Church was provided by the Massachusetts Historical Commission grant with matching funds provided by the Fairbanks Family Association, the Winthrop Improvement and Historical Association, and an anonymous donation to SPNEA. Study of the remainder of the buildings was funded by the anonymous donation to SPNEA. The analysis of the archaeological timber was funded by the Boston Central Artery Archaeology project.

As part of the overall approach to the project, the undated material produced in 1975 from selected seventeenth century buildings for SPNEA by Dr William Robinson of the University of Arizona Tree-Ring Laboratory has been reviewed. His measurements remain in the SPNEA files, although the cores have not as yet been located. Other earlier material that was reviewed as part of this phase of the project was from a previous dendrochronological study of the Spencer-Peirce-Little House in Newbury. Buildings producing dated timbers include the following, but without complete sample documentation, these dates may not necessarily represent actual felling or construction dates:

Whipple House, Ipswich: 1665-6 Capen House, Dorchester/Milton: 1669

Narbonne House, Salem: 1674 Parson Capen House, Topsfield: 1682

Ironworks House, Saugus: 1687-8 Scotch-Boardman House, Saugus: 1689

Howard House, Ipswich: 1707 Spencer-Peirce-Little, Newbury: 1728-9 (repair)

The analysis of all of the samples was completed by April of 2002, including four additional samples that were taken from the Fairbanks House by restoration carpenter Michael Burrey, and shipped to Oxford. All of the above material was combined to form a new master chronology of 316 years, BOSTON02, spanning the years 1454 - 1769.

The study achieved both objectives. Study of the Townsend and Groton Meeting Houses confirmed that the Boston Area Chronology could be used to date buildings as much as fifty miles northwest of Boston. For the area south of Boston, the picture is less clear. Core samples from timbers in the Prospect Street Friends’ Meeting House in Somerset, the one building in the area that was studied, did not cross-match with each other or with the Boston Area Master Chronology. More dated material from this area will be required before results can be achieved.

Studying buildings believed to have been built before 1675 achieved the goal of increasing ring width data for the early and middle years of the seventeenth century. The archaeological timber from the Central Artery excavations that was analysed privately yielded ring width measurements back to 1454. Of the seventeenth century buildings studied, dates of construction suggested by documents were confirmed in two cases. In five cases, construction dates identified by tree-ring study were later than expected, by as much as twenty to forty years. In one case a date eight years earlier than expected was identified.

In addition to this new master chronology BOSTON02 for the Boston area, some thirteen new, independent, site masters were created, plus an additional five from the 1975 Robinson material, making a total of eighteen new site masters which are entirely independent. Once the individual components of the BOSTON01 chronology have been identified, it is hoped to reform all material dated at present into a single, large Boston master chronology. This has significantly increased the database of chronologies available for dating historic timber houses from the Boston area, making the dating of First Period buildings more reliable.

In the course of conducting the study, a number of other points were explored. Firstly, by studying the completeness of the outermost ring beneath the bark, the season of felling was determined. About 78% of the samples with complete sapwood were found to be felled in the winter months, with the majority of the remainder being felled in the spring. Variation in felling dates were noticed in the majority of the phases dated. These ranged from one and five years apart, suggesting that a certain amount of stockpiling of timber was practised within the New England area. The distribution of red oak (Quercus rubra) versus white oak (Q alba) was examined, but there was no discernible trend either chronologically or geographically. Approximately one third of the samples taken were red oak, which proved somewhat less likely to date, with only 46% red oak dating as opposed to 67% for the white. Finally, a preliminary look at the sapwood in white oak showed that there this ranged between 6 and 28 years, but that the identification of sapwood was problematical in white oak, and probably impossible in red oak.

 

II: GENERAL

II.1: INTRODUCTION AND BACKGROUND

Several attempts, initiated by Abbott Lowell Cummings on behalf of SPNEA, have been made over the years to build up a master chronology to enable the historic timber-framed buildings in eastern Massachusetts to be accurately dated. The first was undertaken in 1968 by Frank Demers. He sampled some seven buildings and attempted to cross-date them to build up a floating chronology. He established that cross-matching was possible, but unfortunately skeleton plots were not the ideal method of matching up the more complacent hardwood timbers from the East coast of the United States.

In 1975 Dr. William Robinson together with David Hart and Max Ferro sampled a dozen buildings, some of which were previously sampled by Frank Demers. Unfortunately only a few samples from each building were taken, making cross-matching less conclusive. Nevertheless, this corpus of measured ring sequences has recently proved to be a valuable resource. A good account of the early days of Boston dendrochronology can be found in Krusic and Cook 2001.

In February 1990, Steve Marlens under the direction of Dr Ed Cook of the Lamont-Doherty Earth Observatory Tree Ring Laboratory, Columbia University, took ten samples from the Spencer-Peirce-Little House, Newbury. Despite good ring counts and bark edge on many of the samples, no consistent internal cross-matching could be found (Marlens 1990).

In 1999, Dr Ed Cook and Paul Krusic of the Lamont-Doherty Tree-Ring Laboratory sampled the Iron Works House and a number of archaeological timbers at the Saugus Iron Works. They were able to cross-match the timber patterns from Saugus with a number of samples from Robinson’s 1975 work. This resulted in the construction of a 168-year long floating chronology. They had also in 1997 constructed a well-replicated red oak chronology from standing trees on Mt. Wachusett in the town of Princeton in the central Massachusetts uplands. This chronology extended back to 1672. In order to successfully cross-match this with their provisional floating chronology, late seventeenth and eighteenth century buildings needed to be sampled to enable a ‘bridge’ to be made between the modern and the historic chronologies. Thus the first phase of the Boston Dendrochronology Project was undertaken by Dr Ed Cook and Paul Krusic during the year 2000-2001. Here six buildings of known construction date were selected from 1681 to 1785. It is this work which resulted in the first significant breakthrough, and allowed the BOSTON01 chronology to be formed, spanning the years 1513-1996 (Krusic and Cook 2001).

II.2: METHODOLOGY

II.2.1: The Dating Process

All timbers sampled were of white oak (Quercus alba) or red oak (Q. rubra), although two timbers of black ash (Fraxinus nigra) were sampled from the second phase at the Coffin House as they had in excess of 100 rings. Generally, samples were restricted to what appeared to be primary first-use timbers, or any timbers that might have been re-used from an early phase. Those timbers which looked most suitable for dendrochronological purposes with complete sapwood and/or reasonably long ring sequences were selected. In situ timbers were sampled through coring, using a 16mm hollow auger. Occasionally, timbers removed in the course of alterations were sectioned, as at the First Parish Church, Groton. Where this was not possible, V-cut incisions were discretely made where boards were not visible, as at the Fairbanks House, Dedham, and the Friends’ Meeting House, Somerset. Details and locations of the samples are presented in the summary table located in section III.

The dry samples were sanded on a bench-mounted belt sander, or linisher, using 60 to 1200 grit abrasive paper, and were cleaned with compressed air to allow the ring boundaries to be clearly distinguished. They were then measured under a x10/x30 microscope using a travelling stage electronically displaying displacement to a precision of 0.01mm. Thus each ring or year is represented by its measurement which is arranged as a series of ring-width indices within a data set, with the earliest ring being placed at the beginning of the series, and the latest or outermost ring concluding the data set.

The principle behind tree-ring dating is a simple one: the seasonal variations in climate-induced growth as reflected in the varying width of a series of measured annual rings is compared with other, previously dated ring sequences to allow precise dates to be ascribed to each ring. When an undated sample or site sequence is compared to a dated sequence, known as a reference chronology, an indication of how good the match is must be determined. Although it is almost impossible to define a visual match, computer comparisons can be accurately quantified. Whilst it may not be the best statistical indicator, Student’s (a pseudonym for W S Gosset) t-value has been widely used amongst British dendrochronologists. The cross-correlation algorithms most commonly used and published are derived from Baillie and Pilcher’s CROS programme (Baillie and Pilcher 1973). This calculates the product moment correlation coefficient r for each position of overlap between two sets of data. Unlike earlier programs, this process is parametric since it takes into account the magnitude of the ring widths as well as the change in direction from one year to the next, or in other words whether one ring is wider than the next, or vice versa. The value of r does not take into account the length of overlap between two ring sequences, therefore the value of t is calculated from r to introduce a measure of significance in relation to the length of overlap (Hillam for English Heritage 1998).

Therefore, the Student’s t-value gives a measure of probability of the observed value of r having arisen by chance. Baillie and Pilcher have used 3.5 as an arbitrary value above which a match might be expected. This value of t gives a 0.1% significance level for ring patterns with 100 or more rings, in other words a value of 3.5 or more should arise by chance about once in every 1000 mis-matches. The proviso of the original program is that "just because a match has a value of t>3.5 does not mean it has to be correct. The final decision must always rest with the dendrochronologist - the computer match is only a backup…However, a dendrochronologist’s suggested match, if not backed up by a significant computer correlation, may well be suspect" (Baillie 1982). Although a faster version (Munro 1984) giving slightly different t-values is sometimes used for indicative purposes, standard practice in Britain is to quote the t-values as produced by the original 1973 program (Hillam for English Heritage 1988).

Statistically, t-values over 3.5 should be considered to be significant, although in reality it is common to find demonstrably spurious t-values of 4 and 5 because more than one matching position is indicated. For this reason, dendrochronologists prefer to see some t-value ranges of 5, 6, or higher, and for these to be well replicated from different, independent chronologies with local and regional chronologies well represented. Users of dates also need to assess their validity critically. They should not have great faith in a date supported by a handful of t-values of 3’s with one or two 4’s, nor should they be entirely satisfied with a single high match of 5 or 6. Examples of spurious t-values in excess of 7 have been noted, therefore it is essential that matches with reference chronologies be well replicated, and that this is confirmed with visual matches between the two graphs.

In reality, the probability of a particular date being valid is itself a statistical measure depending on the t-values. Consideration must also be given to the length of the sequence being dated as well as those of the reference chronologies. A sample with 30 or 40 years growth is likely to match with high t-values at varying positions, whereas a sample with 100 consecutive rings is much more likely to match significantly at only one unique position. Samples with ring counts as low as 50 may occasionally be dated, but only if the matches are very strong, clear and well replicated, with no other significant matching positions. These characteristics are essential for intra-site matching when dealing with such short sequences. Consideration should also be given to evaluating the reference chronology against which the samples have been matched: those with well-replicated components which are geographically near to the sampling site are given more weight than an individual site or sample from further away.

It is general practice to cross-match samples from within the same phase to each other first, combining them into a site master, before comparing with the reference chronologies. This has the advantage of averaging out the ‘noise’ of individual trees and is much more likely to obtain higher t-values and stronger visual matches. After measurement, the ring-width series for each sample was plotted as a graph of width against year on log-linear graph paper. The graphs of each of the samples in the phase under study are then compared visually at the positions indicated by the computer matching and, if found satisfactory and consistent, are averaged to form a mean curve for the site or phase. This mean curve and any unmatched individual sequences are compared against dated reference chronologies to obtain an absolute calendar date for each sequence. Sometimes, especially in urban situations, timbers may have come from different sources and fail to match each other, thus making the compilation of a site master difficult. In this situation samples must then be compared individually with the reference chronologies.

Therefore, when cross-matching samples between each other, or against reference chronologies, a combination of both visual matching and a process of qualified statistical comparison by computer is used. The ring-width series were compared on an IBM compatible computer for statistical cross-matching using a variant of the Belfast CROS program (Baillie and Pilcher 1973). A version of this and other programmes were written in BASIC by D Haddon-Reece, and latterly re-written in Microsoft Visual Basic by M R Allwright and P A Parker.

II.2.2: Ascribing Felling Dates

Once a tree-ring sequence has been firmly dated in time, a felling date, or date range, is ascribed where possible. With samples that have sapwood complete to the underside of, or including bark, this process is relatively straight forward. Depending on the completeness of the final ring, i.e. if it has only the spring vessels or early-wood formed, or the latewood or summer growth, a precise felling date and season can be given.

If the sapwood is partially missing, or if only a heartwood/sapwood transition boundary survives, then obviously it is impossible to give a precise felling date. In Britain, Quercus rober grows with clearly identifiable sapwood from which an estimated felling date range can be given for each sample. Generally, the conventional method used to identify sapwood is to determine whether the earlywood, or spring, vessels are filled with tyloses, that is the true definition of heartwood. Colour change is often striking, and generally follows suit, but there are significant exceptions where there is no colour change, or it does not align with the H/S boundary. The number of sapwood rings can be estimated by using an empirically derived sapwood estimate with a given confidence limit. A recent review of the geographical distribution of dated sapwood data from historic building timbers in Britain has shown that a 95% range of 9-41 rings for southern counties and 12-46 for the north is typical for England (Miles 1997).

Unfortunately, it has not been possible to apply an accurate sapwood estimate to oaks in Massachusetts at this time. Primarily, it would appear that there is a complete absence of literature on sapwood estimates for oak anywhere in the country. The matter is further complicated in that the sapwood in white oak (Quercus Alba) occurs in two bands, with only the outer ring or two being free of tyloses in the spring vessels (Gerry 1914; Kato and Kishima 1965). Out of some 50 or so samples, only a handful had more than 3 rings of sapwood without tyloses. The actual sapwood band is differentiated sometimes by a lighter colour, although this is often indiscernible (Desch 1948). In archaeological timbers, the lighter coloured sapwood does not collapse as it does in Q Rober, but only the last ring or two without tyloses shrink tangentially. In these circumstances the only way of being able to identify the heartwood/sapwood boundary is by recording how far into the timber wood boring beetle larvae penetrate, as the heartwood is not usually susceptible to attack unless the timber is in poor or damp conditions. Despite all of these drawbacks, some effort has been made in recording sapwood ring counts on white oak, despite being somewhat subjective. Once the material from the first phase of the project becomes available for study, it is hoped to do a study on the sapwood ring counts for Q. Alba. Sapwood ring counts between 6 and 28 have been recorded in the Phase II material, suggesting that a somewhat narrower sapwood estimate than that used in Britain will eventually be produced for white oaks in eastern Massachusetts.

As for red oaks (Quercus rubra) it will probably not be possible to determine a sapwood estimate as these are what are known as ‘sapwood trees’ (Chattaway 1952). Whereas the white oak suffers from an excess of tyloses, these are virtually non-existent in the red oak, even to the pith. Furthermore, there is no obvious colour change throughout the section of the tree, and wood-boring insects will often penetrate right through to the centre of the timber. Therefore, in sampling red oaks, it is vital to retain the final ring beneath the bark, or to make a careful note of the number of rings lost in sampling, if any meaningful interpretation of felling dates is to be made.

If no sapwood or heartwood/sapwood boundary survives, then the minimum number of sapwood rings from the appropriate sapwood estimate is added to the last measured ring to give a terminus post quem or felled after date. As no sapwood estimate has yet to be produced for New England oaks, no attempt has been made in determining a terminus post quem.

Some caution must be used in interpreting solitary precise felling dates. Many instances have been noted where timbers used in the same structural phase have been felled one, two, or more years apart. Whenever possible, a group of precise felling dates should be used as a more reliable indication of the construction period. It must be emphasised that dendrochronology can only date when a tree has been felled, not when the timber was used to construct the structure under study. However, it is common practice to build timber-framed structures with green or unseasoned timber and that construction usually took place within twelve months of felling (Miles 1997a).

II.2.3: Sampling Strategy

In an area of geographical and geological diversity, tree growth will as a consequence be somewhat different. In constructing a master tree-ring chronology for such a region, it is a priority to have samples from as many different sites as possible to allow an overall average to be produced. As one of the principal objectives of the Boston Dendrochronology Project was to construct such an overall master for the Boston area, a greater geographic diversity of sites would result in a more representative master chronology. Given that funds were limited, experience in Britain has shown that better results would be obtained by selecting a larger number of buildings but with fewer samples from each phase of construction, than to have twice as many samples from half as many buildings. The disadvantage of following such a strategy was that the individual site chronologies would not be as well replicated. However, given the limited resources available, it was decided to pursue as many individual building phases as possible, as it would not only enhance the overall Boston master chronology, but would provide many more dated buildings and features which would be of particular interest to architectural historians.

A second but equally important objective was to provide precise felling dates for as many samples as possible so that the interpretations of the buildings would be as clear as possible. This was especially important in relation to red oak (Quercus rubra) where the eventual use of felling date ranges is not at all likely. Therefore, a primary goal in the sampling strategy was to sample those timbers with complete sapwood, and where there was a choice, to sample those with the highest ring counts first. Sometimes, there were not sufficient timbers that retained bark edge. A secondary objective was then to select those timbers with the longest ring sequences to aid in chronology building.

Generally, those buildings within reasonable travelling distance were given a preliminary assessment, and were then short-listed in order of suitability and access before returning to sample. On the other hand, the more outlying sites were assessed and sampled during a single visit where time permitted. It soon became evident that some generalisations could be made as regards the suitability of certain framing timbers. In the First Period buildings, often the principal posts would be fast-grown, boxed-heart timbers unsuitable for dendrochronology, whereas the summer beams, and often the end girts and tie beams would be from better quality, slower grown timbers. The summer beams were almost universally boxed heart, whilst the girts and tie beams were usually halved trees. In addition, smaller members such as studs and joists were often from large, slow grown trees which had been sawn into many smaller members. In the eighteenth-century buildings, again posts were almost always from fast-grown boxed-heart trees, whereas many of the smaller members such as struts and studs were again converted from large, slower-grown trees.

All timbers assessed for their dendrochronological potential were also critically assessed for their structural integrity. Principal framing timbers morticed and tenoned together are obviously much less likely to have been replaced than a lodged ceiling joist. Timbers were also studied to identify any obvious signs of reuse.

In selecting the precise point of sampling, the primary consideration was to determine which part of the complete sapwood was most sound and least affected by historic beetle attack. Wherever possible, points of sampling were selected so as to be in the least visible location, but occasionally very little choice was available. In these instances core holes were plugged with ramin doweling and stained to match the surrounding surface to minimise visual impact. The structural integrity of the timbers sampled was considered to ensure that no sample would be extracted from an overstressed area such as a joint.

At the time of sampling the timbers selected were recorded on a plan, if available, or on a sketch pending the production of a plan at a later date. These are included in Section III. A written description of the sample location is also included in the principal table of results which is tied with either truss numbers or compass points. It is essential that all samples taken from historic buildings be firmly provenanced.

II.2.4: Publication of Dates and Data Archiving

Until such time as a nationally accessible forum is found to systematically publish tree-ring dates, as the journal Vernacular Architecture does in Britain, the results contained within this report will be accessible on the web-site maintained by the Oxford Dendrochronology Laboratory, which can be found on the URL www.dendrochronology.com

Click here to go to dated buildings

 

The ring-width data produced by this phase of work, including site master chronologies and the regional master chronology BOSTON02, will be deposited with the ITRDB and the SPNEA archives, as well as being held by the Oxford Dendrochronology Laboratory, where it will be available to all serious researchers.

 

III: DETAILED ANALYSIS AND RESULTS

III.1: CREATION OF DATABASE OF MASTER CHRONOLOGIES

In attempting to date historic and archaeological timbers, it was first necessary to construct a database of firmly-dated reference chronologies with which to compare undated samples. The first phase of the project resulted in the regional master chronology covering the years 1513-1996 (Krusic and Cook 2001), hereinafter called BOSTON01. In order to allow some degree of cross-checking with a number of independent site masters, the material from which the BOSTON01 chronology was composed was broken down into a number of independent site-specific masters, composed of the best-matching samples from five of the six buildings. This then gave independent site masters for the following five buildings:

Site name: Chronology: Dates spanned:

Rocky Hill Meeting House, Amesbury RHM 1661-1784

Harvard Hall, Cambridge HH 1634-1764

Old Ship Church, Hingham HSC 1640-1754

Congregational Church, Burlington BCC 1681-1726

Presbyterian Church, Newburyport NPC 1680-1753

all included in

Boston Archaeol. Master Dating Chronology BOSTON01 1513-1997

 

Next, the material collected by Dr Robinson in 1975 was reviewed. This was available only on poor-quality third-generation photocopies of fan-fold printouts, some of which had originally become stuck in the feed rollers, making a number of lines unreadable. Fortunately, the photocopied sheets also included the mean ring width, mean sensitivity, and standard deviation for each dataset, and these were used as ‘fingerprints’ to ensure that no typographical errors were introduced. A total of 26 sample sheets were found, and all but one was successfully transcribed. With the absence of sample names/codes for these, they were all given a prefix alc for Abbot Lowell Cummings, who was instrumental in commissioning the data collection for SPNEA, with the first number being the site, and the second number being the individual core. Hence alc43 was the fourth house listed (Capen House, Dorchester) and the third sample, the rear chimney post. These samples originated from a dozen buildings and all but seven of the 26 samples were successfully dated with the BOSTON01 chronology. However, it must be remembered that a number of these had been similarly transcribed by Paul Krusic and are probably included in the BOSTON01 chronology, although the exact components of this chronology is not known. Nevertheless, the 1975 material was grouped into the following five site chronologies:

Site name: Chronology: Dates spanned:

Parson Capen House, Topsfield ALC2 1500-1682

Narbonne House, Salem

+ Whipple House, Ipswich ALC3 1564-1674

Capen House, Dorchester/Milton

+ Iron Works House, Saugus ALC4 1537-1687

Scotch-Boardman House, Saugus ALC9 1599-1689

Howard House, Ipswich ALC10 1601-1707

 

With the compilation of the Robinson material, there were now ten totally independent site master chronologies to work from, plus the regional master BOSTON01 in which most of the site masters were included. Thus a good, replicated, database of chronologies was constructed against which new material could be confidently compared. The matching between these are shown in the table below, with matches over 3.5 shown highlighted in bold:

 

ACKNOWLEDGEMENTS

The authors of this study would like to thank the following people for their assistance. Their contribution to the project is gratefully acknowledged.

Dana Balch: First Parish Church, Groton

Michael Burrey: Restoration carpenter, for assistance in taking samples at the Fairbanks House and the Prospect Street Friends’ Meeting House in Somerset

Mr. and Mrs. Charles Chace: Prospect Street Friends’ Meeting House, Somerset

Laura Driemeyer: Architectural Historian, Society for the Preservation of New England Antiquities (SPNEA) Local Project Co-ordinator for the MHC grant

Joanne Flaherty: North Shore Regional Administrator, SPNEA

Susan Gerkin: Historian, Townsend United Methodist Church

David Hubbard: Treasurer, Winthrop Improvement and Historical Association

James Kyprianos: Resident caretaker, Deane Winthrop House

Julie Letendre: Curator, Fairbanks House

Michael Lynch: Vice President for Properties and Preservation, SPNEA

Stephen Miller: First Parish Church, Groton

Brian Powell: Resident overseer, Cooper-Frost-Austin House

Leith Smith: Project Archaeologist for the Central Artery/Tunnel Project

Michael Steinitz: Director of Preservation Planning, Massachusetts Historical Commission (MHC)

Joanne and Emerson Tuttle: Owners of the Tuttle House, Ipswich, for their support of SPNEA’s dendrochronology project