In 1807 the arm of the Oder that flowed round Ostrów Tumski was filled in; all that is left of the water is a pond in the Botanical Garden. Choose a year, pin another and see what changed — and what the material is silent about.
Year viewed — five slices
13 years; the material does not describe the intermediate states
4 years
147 years with no dated slices in this material
after that: open-ended, no number of years
Without JavaScript the diagram shows the state in 1807 with the outline of the 1794 arm pinned (a dashed blue line above the filled-in arm). All five slices are described in the section The five slices in the record.
1807year viewedpinned: 1794
A relational diagram, not a map. The author's own V3 drawing, based on descriptions in sources [1] and [2]. Shapes, distances and positions are conventional, with no scale or georeferencing; other branches and canals are not modelled. The numbers correspond to the list below the drawing.
water (the channel exists)
filled in with rubble
not established
background: main channel (state at this date not described)
navigation route (from 1794)
garden boundary (conventional; the pond's position relative to it is not established)
pinned: arm as water
pinned: arm filled in
pinned: pond, garden, footbridge
Ostrów Tumski — a fixed reference point; the outline is conventional and is not part of the comparison.
The pinned year stays on the diagram as a dashed outline beside the year viewed: the arm as a separate line above the arc (blue for water, brown for fill), the other elements as an amber outline.
1807 · Arm filled in with rubble
The arm that flowed round Ostrów Tumski was filled in with rubble from demolished fortifications.
The year 1811 refers to the founding of the Botanical Garden [2]. The pond is what remains of the arm, so it is an older layer of the place [1].
1807 is not the river drying up
The source describes the arm being filled in with rubble from demolished fortifications, not natural drying up [1].
1794 is not the filling-in
Moving the navigation route and eliminating the channel are two events, separated by 13 years [1].
The pond is not the whole former arm
The pond's present-day bank does not mark the full course or width of the former channel.
Glossary: an arm is a branch of a river; a cut or canal is a new waterway made by people; an oxbow lake is what remains of a former channel. The city's account describes separately the filled-in branch round Ostrów and the later navigation canals; we do not lay their histories over one another here.
What the diagram does not say
This is the author's own relational diagram, not a map or a reconstruction. It has no scale, no georeferencing and no verified bank geometry.
The state of the arm in 1794 is an inference from the date of the filling-in (1807), not a record from that year.
The material gives no channel width, flow or extent; we do not calculate them from a terrain model or from a present-day name.
Unknown is not zero: “not established” means the material is silent, not that nothing happened. Such fields are excluded from the comparison.
We do not decide whether, after 1807, Ostrów ceased to be an island in the hydrological sense; other branches and canals are not modelled.
The diagram is not a navigation aid or permission to go to the water's edge. We do not give the garden's opening hours or entry rules — check them with the operator.
The five slices in the record
A full description of each slice, also without JavaScript. The label beside each element shows what the drawing rests on.
1794Navigation leaves the arm
From 1794 the navigation route runs through the central part of the Śródmiejski Water Junction rather than along the arm flowing round Ostrów Tumski [1]. This is a change in the use of the river — not yet its filling-in.
2 · ArminferenceThe channel still exists. The drawing assumes this because it was filled in only in 1807 — an inference from a later date, not a record of the state in 1794.
3 · Channel and routefrom the sourceA navigation route has run this way since 1794 [1]. The diagram does not indicate the direction of flow.
4 · Pondnot establishedNothing separate is established. Today's pond is what remains of the arm, so at that time it was part of the channel — we do not know its shape or boundaries.
5 · Gardenfrom the sourceThe garden does not exist yet; it was founded in 1811 [2].
6 · 1958 footbridgefrom the sourceThe 1958 footbridge does not exist yet. This row concerns only that footbridge; the material does not describe other crossings, which does not mean there were none.
The arm flowing round Ostrów Tumski was filled in with rubble from demolished fortifications [1]. This was the elimination of the channel, not the river drying up naturally. The city identifies a fragment of an oxbow lake in the Botanical Garden as what remains of it [1].
2 · Armfrom the sourceFilled in with rubble from demolished fortifications [1].
3 · Channel and routebackgroundDrawn as background. The material does not describe the state of the channel at this date.
4 · Pondfrom the sourceA fragment of an oxbow lake remains after the filling-in [1]. Its shape and position in the drawing are conventional.
5 · Gardenfrom the sourceThe garden does not exist yet; it was founded in 1811 [2].
6 · 1958 footbridgefrom the sourceThe 1958 footbridge does not exist yet. This row concerns only that footbridge; the material does not describe other crossings, which does not mean there were none.
The university founds the Botanical Garden on former fortification land [2]. This is the date the garden was founded — not the date the pond came into being: the relic of the channel is an older layer of the place.
2 · Armcarried overFilled in since 1807. The sources in this material describe no new changes to the arm at this date.
3 · Channel and routebackgroundDrawn as background. The material does not describe the state of the channel at this date.
4 · PondinferenceWhat remains of the arm [1]. Whether and how the pond lay within the garden's boundaries in 1811 has not been established; its position in the drawing is conventional.
5 · Gardenfrom the sourceFounded on former fortification land [2]. The boundary in the drawing is conventional.
6 · 1958 footbridgefrom the sourceThe 1958 footbridge does not exist yet. This row concerns only that footbridge; the material does not describe other crossings, which does not mean there were none.
A wooden footbridge is built on the pond with the help of the Higher Officers' School of Engineering Troops; the chronicle also records the garden being opened every day of the week [2].
2 · Armcarried overFilled in since 1807. The sources in this material describe no new changes to the arm at this date.
3 · Channel and routebackgroundDrawn as background. The material does not describe the state of the channel at this date.
4 · Pondfrom the sourceThe pond exists — a footbridge stands on it [2].
5 · Gardenfrom the sourceThe garden is open every day of the week — according to the garden's chronicle [2].
6 · 1958 footbridgefrom the sourceA wooden footbridge on the pond, built with the help of the Higher Officers' School of Engineering Troops [2].
The pond in the Garden is today a preserved fragment of the arm [1]. Its bank does not mark the former course or width of the channel. “Today” here is not a date on a timeline but a state to be checked on the ground.
2 · Armcarried overFilled in in 1807; the present-day lie of the land is neither measured nor reconstructed here.
3 · Channel and routebackgroundDrawn as background. The material does not describe the present-day state of the channel or the route.
4 · Pondfrom the sourceA preserved fragment in the garden [1]; check its present-day state on the ground or with the garden's operator.
5 · Gardenfrom the sourceThe garden exists [2]; opening hours and entry rules are to be checked — we do not give them here.
6 · 1958 footbridgeto be checkedWe know the 1958 footbridge from the chronicle [2]; whether today's footbridge is the same structure is to be checked on the ground. Drawn with a dashed line.
Miasto Wrocław: budowle hydrotechniczne wrocławskiego węzła wodnego [City of Wrocław: hydraulic structures of the Wrocław water junction]Basis for: the moving of the route in 1794, the filling-in of the arm in 1807, the oxbow lake in the garden. Link carried over from V2; not opened in this session.
Ogród Botaniczny UWr: historia ogrodu [University of Wrocław Botanical Garden: history of the garden]Basis for: the founding of the garden in 1811, the 1958 footbridge, the opening of the garden every day of the week. Link carried over from V2; not opened in this session; the address with the “iwww” prefix needs checking.
That the dates and wording match the originals [1] and [2].
The position of the pond relative to the garden's boundaries in 1811.
Whether today's footbridge is the same structure as the one from 1958.
Access to the garden, opening hours and entry rules — with the operator.
Missing material: two comparable historical plans with usage rights, and dated photographs of the relic. Without georeferencing, they should be included as separate scans, not as an overlay.
What changed relative to V2
Removed: the notebook saved in the browser (it added no knowledge of the subject), the separate anachronism detector (replaced by four annotations in the section “Limits”), the channel-state metrics (they repeated the description and did not come from measurement), four field points with invented geometry, the layer switches and the photograph embedded from the internet. Kept: the five dates, the separation of 1794, 1807, 1811 and 1958, and the comparison of two dates — now on one diagram at the same time.