Wednesday, 16 September 2015

Re-Modelling the Displays

Thanks to an award of nearly £40,000 from the DCMS/ Wolfson Foundation's Museum and Galleries Improvement Fund we are in the process of improving the Museum's displays of Air and Transport Models.

Steve Grafton Joinery are in the process of making new cases that are in keeping with the period style of the Museum, plus will enable visitors to clearly see all of the models on display. When finished these high quality cases will be in the Court Gallery on the ground floor and will be positioned to allow space for staff and volunteer guides to give introductory talks about the collections to visitors.

In the old model displays not all of the objects have a label. The new cases will include these to ensure visitors can easily find out information about everything on display.

I am currently  cataloguing, photographing, and researching the collection to ensure the information on the labels is up-to-date. At the same time, I am adding information and images to the relevant object records. This means, even if you cannot visit the Museum in person, you will still be able to see the models and access all the information about them via the online database.

The photos you can see below are some of the interesting models I am currently working with. On the  left is a wooden replica model of a troll cart from Great Yarmouth in England, in the middle a wooden model of a Chinese wheelbarrow used to transport people and goods, and on the right a Saami passenger reindeer sled.

Left to right: model troll cart PRM 1892.12.1, model wheelbarrow  PRM 1897.59.6, model reindeer sled PRM 1884.1.5 
© Pitt Rivers Museum
These three models entered the Museum collection at the end of the nineteenth century so all are definitely more than a hundred years old. During this time there have been many changes to transportation so even though I am English I had never heard of a Yarmouth troll cart. I was interested to discover this type of cart was specifically designed to fit through the narrow medieval streets, known as the Rows, of Great Yarmouth. Contained within the medieval walls of the city were 145 of these narrow Rows, many of which were destroyed when the city was bombed during World War Two. Most of the rows were only 90 to 150 centimetres wide so even the doors were made to open inwards so they didn't knock passers by and as you can imagine this space was too small for a regular horse and cart. The Yarmouth troll cart was twelve feet long and a maximum width of three feet six inches. With a short low back axle and wheels that ran under the body of the carriage they could be tipped on one end when not being used, consequently taking up very little space to store.

The earliest known wheelbarrows date back to Ancient China where they were used for carrying passengers as well as heavy loads. The wheel, as is the case in the model you can see above, was characteristically placed in the centre of the barrow. This design means the barrow takes the full weight of the load, the driver simply having to guide the vehicle. Whereas the European wheelbarrow with the wheel at the front splits the weight of the load between the vehicle and the driver. Consequently the Chinese wheelbarrow can carry a much heavier load, this successful design remained widely in use in China for short haul work well into the nineteen sixties.

The Saami people are indigenous to the Arctic regions incorporating parts of Finland, Norway, Sweden, and the Kola Peninsula of Russia. This style of sled is often called a ahkio or pulka and the shape of the design makes it both easy to pull and prevents it sinking in soft snow.  This remains a successful design that is often used by mountain rescue teams, although now more commonly a human or snowmobile towed sled than pulled by reindeer. The model shows the traditional reindeer harness, as well as the style of sled.

Keep an eye on this blog and I will let you know when these new displays are complete.

Zena McGreevy
Senior Assistant Curator

Wednesday, 2 September 2015

Close Examination of a 19th Century Tahitian 'Poncho'

In early June I wrote a blog post about a 19th-century Tahitian poncho-like garment called a tiputa, which I conserved while on a student placement in the Pitt Rivers Museum’s Conservation department. 

PRM1984.3.1, front, before conservation (left) and after conservation (right)  © Pitt Rivers Museum
Alongside the treatment of the object, I spent some time trying to identify its associated plant materials. I started by looking at ethnobotanical sources listing the plants traditionally exploited by Tahitians at the time the tiputa was made.

From this I discovered, for example, that the fine white barkcloth which makes up the body of the garment was almost certainly made from the inner bark of the paper mulberry tree (Broussonetia papyrifera) - the most commonly used species for barkcloth in Tahiti and also the tree said to produce the palest, highest quality cloth. Other sources of barkcloth traditionally used in Tahiti, including the breadfruit tree (Artocarpus altilis) and two species of Ficus generally produced darker, coarser cloth.

Close-up image of the barkcloth making up PRM1984.3.1 © Pitt Rivers Museum    
Features visible to the naked eye also helped to identify ties on either side of the neck opening. This material had a distinctive elongated, open fibre structure, which could easily be seen without magnification. By comparing it with modern botanical and ethnological specimens I could identify it almost certainly as the inner bark of a Hibiscus.

Close-up image of a neck tie from PRM1984.3.1 © Pitt Rivers Museum    
The tiputa was further decorated with rosettes and decorative trims made of strips of a very shiny, golden-coloured plant leaf material, folded and stitched together. The tiputa was also fringed with long strips of a very thin, almost translucent leaf material. Finally, a yellow powder was loosely dusted over the entire surface.

The remaining plant materials present on PRM1984.3.1, from left to right: rosettes, leaf strips, and powder © Pitt Rivers Museum    
Examining these remaining plant materials with the naked eye, plus researching the existing literature, did not make their identification straightforward - there were several possibilities for each sample. 

Looking at similar objects in other institutions did not make identification any easier as the descriptions of the materials were often contradictory. For example, the rosette material is described in the Pitt Rivers documentation as “folded grasses or cane strips”; whereas in the documentation at the British Museum this material on similar objects is listed as either the leaf of arrowroot (Maranta arundinacea) or coconut palm (Cocos nucifera). From my own research, I also noted remarkable similarities between the rosette material and the leaves from the screw pine (Pandanus tectorius) used in the popular Hawaiian lauhala weaving craft.
Similarly, leaf strips from the Pitt Rivers tiputa were identified in the 1980s as the “cuticle of young banana leaves retted in (probably) stale urine and boiled”; while the accession register for similar objects at the Kew Royal Economic Botany Collection describes the strips as made of sugar cane (Saccharum officinarum) or coconut palm. On objects at the Musee du Quai Branly the strips are identified as seaweed. More recently, Dr Caroline Cartwright, a Senior Scientist and specialist in fibre identification, identified similar strips on a Tahitian robe at the British Museum as the epidermis of sugar cane leaf.

The abundance of already detached material available for these remaining fibre types provided me with the opportunity to investigate them using two microscopic techniques.

© Pitt Rivers Museum
First, I looked at the samples using polarised light microscopy (PLM), which allowed me to magnify samples up to 200x and to observe distinctive colour changes of the samples in response to different light settings.  

On the right you can see optical microscope images taken at 200x magnification of the rosette material (top row), the leaf strips (middle row) and the powder (bottom row).

Even greater magnification is possible with scanning electron microscopy (SEM), which I carried out at UCL’s Institute of Archaeology

© Pitt Rivers Museum    

On the left you can see scanning electron microscope (SEM) images taken at 500-600x magnification of the rosette material (top), the leaf strips (middle) and the powder (bottom).

Identification of plant fibres using microscopy is not as straightforward as it may seem, particularly if the samples are from ethnographic or archaeological artefacts. Fibre reference atlases tend to contain images of clean, fresh plant material, while samples taken from museum objects are likely to look rather different as a result of processing, use and ageing.

A high level of expertise is also required to interpret features. Caroline Cartwright kindly looked at my SEM images of samples from the Pitt Rivers tiputa, but she emphasised the need to be realistic in the level of identification which can be achieved: in addition to the problems already mentioned, the taking of microscopic images is subjective and different people will choose to focus on different areas for examination.

Unfortunately, my SEM images for the rosette material and the powder did not contain enough diagnostic detail to allow secure identification. However, for the leaf fringes, Caroline Cartwright confirmed that – like on the British Museum object she examined – they were very similar to reference specimens of sugar cane leaf and definitely not similar to banana leaf specimens.

PLM (left) and SEM (right) images of the stitching thread, at 50x and 200x magnification respectively.    
Tell-tale “ribbon twists” seen in microscope images of the stitching thread used in the Pitt Rivers tiputa’s construction did allow a positive identification to cotton, rather than a type of indigenous cordage. Finding a European imported material used alongside a range of traditional materials in a single object is a fascinating clue to the creative use of material culture in colonial Tahiti.

Finally, for the yellow powder, literature research suggested it may have been used to either colour or scent the barkcloth. Turmeric (Curcuma longa) is a colourant frequently found in Pacific ethnographic material. However, when a tiny sample of the powder was left to react with first an acid and then an alkali, the typical colour changes indicating the presence of curcumin did not happen, so turmeric was excluded as a candidate. Whether the powder could be another type of powdered root, such as ginger, or perhaps a fragrant resinous wood may be shown using yet another technique, Fourier transform infrared spectroscopy (FT-IR), but for now it remains a bit of a mystery.

Naomi Bergmans
Conservation Student