Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Building | Height [m] | Floors | Built | City | Architect |
| --- | --- | --- | --- | --- | --- |
| Eaton's Department Store * | 46.0 | 9.0 | 1904.0 | Winnipeg | John Woodman |
| Union Bank Tower | 48.0 | 10.0 | 1904.0 | Winnipeg | Darling and Pearson |
| Lindsay Building | 44.0 | 11.0 | 1911.0 | Winnipeg | Woodman and Carey |
| Confederation Building | 46.0 | 12.0 | 1911.0 | Winnipeg | J. Wilson Gray |
| National Bank Building | 50.0 | 13.0 | 1911.0 | Winnipeg | John D. Atchison |
| Electric Railway Chambers | 45.0 | 12.0 | 1912.0 | Winnipeg | Pratt and Ross, Charles S. Frost |
| Hotel Fort Garry | 59.0 | 14.0 | 1913.0 | Winnipeg | Ross and MacFarlane |
| Marlbourgh Hotel | 42.0 | 10.0 | 1913.0 | Winnipeg | J. Chisholm & Son |
| Paris Building | 42.0 | 11.0 | 1915.0 | Winnipeg | Woodman and Carey |
| Bank of Hamilton Building | 45.0 | 10.0 | 1916.0 | Winnipeg | John D. Atchison |
| Manitoba Legislative Building | 79.0 | 5.0 | 1920.0 | Winnipeg | Simon and Boddington |
Question:
Who was the architect that built the Electric Railway Chambers before 1915?
Answer:
Pratt and Ross, Charles S. Frost