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:
| Number | Name | Builder | Type | Works number | Date |
| --- | --- | --- | --- | --- | --- |
| 1.0 | Elidir | Hunslet | 0-4-0 ST | 493.0 | 1889.0 |
| 2.0 | Thomas Bach | Hunslet | 0-4-0 ST | 894.0 | 1904.0 |
| 3.0 | Dolbadarn | Hunslet | 0-4-0 ST | 1430.0 | 1922.0 |
| 3.0 | Maid Marian | Hunslet | 0-4-0 ST | 822.0 | 1903.0 |
| 7.0 | Topsy | Ruston Hornsby | 4wDM | 441427.0 | 1961.0 |
| 8.0 | Twll Coed | Ruston Hornsby | 4wDM | 268878.0 | 1952.0 |
| 11.0 | Garrett | Ruston Hornsby | 4wDM | 198286.0 | 1939.0 |
| 12.0 | Llanelli | Ruston Hornsby | 4wDM | 451901.0 | 1961.0 |
Question:
What number has the builder ruston hornsby, the date 1961, and the name Topsy?
Answer:
1.0